Mizuho Financial (MFG) 20-F 28 Jun 23 2023 FY Annual report (foreign) Financial data

Cover Page

Cover Page	12 Months Ended
	Mar. 31, 2023 shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	Mizuho Financial Group, Inc.
Entity Central Index Key	0001335730
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	826,676
Document Accounting Standard	U.S. GAAP
Entity File Number	001-33098
Entity Incorporation, State or Country Code	M0
Document Registration Statement	false
Entity Address, Address Line One	1-5-5 Otemachi
Entity Address, City or Town	Chiyoda-ku
Entity Address, Postal Zip Code	100-8176
Entity Address, Country	JP
ICFR Auditor Attestation Flag	true
Auditor Name	Ernst & Young ShinNihon LLC
Auditor Firm ID	789
Auditor Location	Tokyo, Japan
Business Contact [Member]
Document Information [Line Items]
Contact Personnel Name	Yasutoshi Tanaka
Entity Address, Address Line One	1-5-5 Otemachi
Entity Address, City or Town	Chiyoda-ku
Entity Address, Postal Zip Code	100-8176
Entity Address, Country	JP
City Area Code	81-3
Local Phone Number	5224-1111
American depositary shares
Document Information [Line Items]
Security Exchange Name	NYSE
Title of 12(b) Security	American depositary shares, each of which represents two shares of common stock
Trading Symbol	MFG
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, without par value
No Trading Symbol Flag	true

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Assets:
Cash and due from banks	¥ 2,241,929	¥ 2,290,377
Interest-bearing deposits in other banks	65,750,366	49,883,912
Call loans and funds sold	1,647,472	1,102,296
Receivables under resale agreements	11,695,014	12,751,085
Receivables under securities borrowing transactions	1,891,576	2,338,796
Trading account assets (including assets pledged that secured parties are permitted to sell or repledge of ¥4,639,282 million in 2022 and ¥7,355,733 million in 2023)	29,641,038	24,652,067
Investments (Note 3):
Available-for-sale securities (including assets pledged that secured parties are permitted to sell or repledge of ¥1,120,839 million in 2022 and ¥2,466,444 million in 2023), net of allowance	23,233,769	31,673,890
Held-to-maturity securities (including assets pledged that secured parties are permitted to sell or repledge of ¥1,019,391 million in 2022 and ¥1,594,501 million in 2023)	2,050,107	1,519,055
Equity securities	3,691,870	3,572,908
Other investments	667,201	582,388
Loans (Notes 4 and 5)	94,175,757	90,290,583
Allowance for credit losses on loans	(700,959)	(809,817)
Loans, net of allowance	93,474,798	89,480,766
Premises and equipment—net (Note 6)	1,653,888	1,704,067
Due from customers on acceptances	405,742	271,877
Accrued income	510,791	322,025
Goodwill (Note 7)	92,928	92,695
Intangible assets (Note 7)	44,681	47,939
Deferred tax assets	386,592	277,319
Other assets (Note 12)	9,700,960	8,987,242
Total assets	248,780,722	231,550,704
Liabilities and equity:
Noninterest-bearing deposits	33,136,655	32,844,872
Interest-bearing deposits	92,625,324	91,425,213
Noninterest-bearing deposits	3,042,821	2,500,823
Interest-bearing deposits	36,130,825	30,407,376
Due to trust accounts	749,382	390,247
Call money and funds purchased	1,814,874	1,278,051
Payables under repurchase agreements (Note 28)	25,737,154	20,069,566
Payables under securities lending transactions (Note 28)	886,391	1,360,743
Other short-term borrowings (Note 11)	3,397,329	7,566,771
Trading account liabilities	19,362,943	14,859,383
Bank acceptances outstanding	405,742	271,877
Income taxes payable	88,277	62,697
Deferred tax liabilities	25,424	29,033
Accrued expenses	442,729	203,383
Long-term debt (including liabilities accounted for at fair value of ¥ 2,756,062 million in 2022, and ¥2,680,164 million in 2023) (Notes 11 and 26)	14,893,023	12,578,216
Other liabilities (Note 12)	6,316,695	6,260,222
Total liabilities	239,055,588	222,108,473
Commitments and contingencies (Note 22)
MHFG shareholders' equity:
Common stock (Note 14)—no par value, authorized 4,800,000,000 shares, and issued 2,539,249,894 shares at March 31, 2022 and 2023	5,832,729	5,816,834
Retained earnings	2,442,153	2,665,608
Accumulated other comprehensive income (loss), net of tax (Note 16)	649,395	440,112
Less: Treasury stock, at cost—Common stock 4,659,024 shares at March 31, 2022, and 5,027,306 shares at March 31, 2023	(8,786)	(8,342)
Total MHFG shareholders' equity	8,915,491	8,914,212
Noncontrolling interests	809,643	528,019
Total equity	9,725,134	9,442,231
Total liabilities and equity	248,780,722	231,550,704
Consolidated VIEs
Assets:
Cash and due from banks	1,941	2,243
Interest-bearing deposits in other banks	155,551	71,573
Call loans and funds sold	260,997	162,578
Trading account assets (including assets pledged that secured parties are permitted to sell or repledge of ¥4,639,282 million in 2022 and ¥7,355,733 million in 2023)	2,614,888	2,222,902
Investments (Note 3):
Investments	233,348	238,624
Loans, net of allowance	8,381,183	8,347,880
Other assets (Note 12)	505,636	529,178
Total assets	12,153,544	11,574,978
Liabilities and equity:
Payables under securities lending transactions (Note 28)	128,548	51,752
Other short-term borrowings (Note 11)	187,852	53,668
Trading account liabilities	64,708	51,019
Long-term debt (including liabilities accounted for at fair value of ¥ 2,756,062 million in 2022, and ¥2,680,164 million in 2023) (Notes 11 and 26)	1,164,719	1,024,067
Other liabilities (Note 12)	1,057,384	1,041,938
Total liabilities	¥ 2,603,211	¥ 2,222,444

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Statement [Line Items]
Trading account assets, assets pledged that secured parties are permitted to sell or repledge	¥ 7,355,733	¥ 4,639,282
Available-for-sale securities, assets pledged that secured parties are permitted to sell or repledge	2,466,444	1,120,839
Held-to-maturity securities, assets pledged that secured parties are permitted to sell or repledge	1,594,501	1,019,391
Long-term debt, liabilities accounted for at fair value	¥ 2,680,164	¥ 2,756,062
Common stock, par value	¥ 0	¥ 0
Common stock, authorized	4,800,000,000	4,800,000,000
Common stock, issued	2,539,249,894	2,539,249,894
Treasury stock, shares	5,027,306	4,659,024

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Interest and dividend income:
Loans, including fees		¥ 1,960,377	¥ 957,579	¥ 1,018,766
Investments:
Interest		78,953	63,050	55,482
Dividends		96,237	83,589	56,847
Trading account assets		426,117	245,146	236,620
Call loans and funds sold		13,877	1,377	2,186
Receivables under resale agreements and securities borrowing transactions		307,744	36,479	42,350
Deposits in other banks		505,486	56,721	44,305
Total interest and dividend income		3,388,791	1,443,941	1,456,556
Interest expense:
Deposits		1,061,014	76,292	160,315
Trading account liabilities		101,311	59,739	52,682
Call money and funds purchased		17,308	1,093	1,829
Payables under repurchase agreements and securities lending transactions		671,006	40,672	54,655
Other short-term borrowings		59,314	5,623	18,432
Long-term debt		270,111	190,713	180,026
Total interest expense		2,180,064	374,132	467,939
Net interest income		1,208,727	1,069,809	988,617
Provision (credit) for credit losses (Note 3 and 5)		93,753	214,408	112,776
Net interest income after provision (credit) for credit losses		1,114,974	855,401	875,841
Noninterest income (Note 24):
Fee and commission income		984,345	980,000	912,684
Foreign exchange gains (losses)—net (Note 25)	[1]	189,526	91,611	89,267
Trading account gains (losses)—net (Note 25)		(603,910)	(491,947)	120,596
Investment gains (losses)—net:
Debt securities		5,167	(14,777)	(22,032)
Equity securities		135,601	(60,563)	850,567
Equity in earnings (losses) of equity method investees—net	[2]	(26,999)	34,587	31,027
Gains on disposal of premises and equipment		4,920	9,943	7,125
Other noninterest income	[3],[4]	199,453	120,936	52,086
Total noninterest income		888,103	669,790	2,041,320
Noninterest expenses:
Salaries and employee benefits		694,027	669,474	685,692
General and administrative expenses		692,879	611,326	623,732
Occupancy expenses		164,603	201,987	206,470
Fee and commission expenses		202,347	203,957	190,489
Provision (credit) for credit losses on off-balance-sheet instruments		6,581	(14,819)	18,007
Other noninterest expenses		173,470	95,754	164,007
Total noninterest expenses		1,933,907	1,767,679	1,888,397
Income (loss) before income tax expense (benefit)		69,170	(242,488)	1,028,764
Income tax expense (benefit) (Note 19)		35,142	(141,017)	210,716
Net income (loss)		34,028	(101,471)	818,048
Less: Net income attributable to noncontrolling interests		48,037	3,251	236,283
Net income (loss) attributable to MHFG shareholders		¥ (14,009)	¥ (104,722)	¥ 581,765
Earnings per common share (Note 18):
Basic net income (loss) per common share		¥ (5.52)	¥ (41.28)	¥ 229.27
Diluted net income (loss) per common share	[5]	(5.52)	(41.28)	229.26
Dividends per common share:
Common stock		¥ 85	¥ 80	¥ 75
[1]Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.[2]These amounts are revenues from contracts that do not meet the scope of ASC 606.[3]Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.[4]These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 26 “Fair value” for further details.[5]For the fiscal years ended March 31, 2021, 2022 and 2023, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects. In addition, for the fiscal years ended March 31, 2022 and 2023, the computation of diluted earnings per common share did not assume exercise of stock options, as the effect of such exercise would be antidilutive due to net loss.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Statement [Line Items]
Net income (loss)	¥ 34,028	¥ (101,471)	¥ 818,048
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available-for-sale securities, net of tax	(7,828)	(17,020)	11,534
Foreign currency translation adjustments, net of tax	135,849	185,298	22,695
Defined benefit plan adjustments, net of tax	68,223	(41,385)	328,066
Own credit risk adjustments, net of tax	13,443	(300)	(35,187)
Total other comprehensive income, net of tax	209,687	126,593	327,108
Total comprehensive income	243,715	25,122	1,145,156
Less: Total comprehensive income attributable to noncontrolling interests	48,442	7,846	235,784
Total comprehensive income attributable to MHFG shareholders	¥ 195,273	¥ 17,276	¥ 909,372

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Statement [Line Items]
Balance at beginning of fiscal year		¥ 9,442,231	¥ 9,688,157
Net income (loss) attributable to MHFG shareholders		(14,009)	(104,722)	¥ 581,765
Change during year		209,687	126,593	327,108
Net income attributable to noncontrolling interests		48,037	3,251	236,283
Balance at end of fiscal year		9,725,134	9,442,231	9,688,157
Common Stock
Statement [Line Items]
Balance at beginning of fiscal year		5,816,834	5,826,863	5,827,500
Performance-based stock compensation program		(256)	(69)	(110)
Change in ownership interests in consolidated subsidiaries		16,271	(9,960)	(527)
Other		(120)	0	0
Balance at end of fiscal year		5,832,729	5,816,834	5,826,863
Retained Earnings
Statement [Line Items]
Balance at beginning of fiscal year		2,665,608	2,967,385	2,700,774
Other		(14)	(309)	(100)
Net income (loss) attributable to MHFG shareholders		(14,009)	(104,722)	581,765
Dividends declared		(209,432)	(196,746)	(190,418)
Balance at end of fiscal year		2,442,153	2,665,608	2,967,385
Retained Earnings | Cumulative effect, period of adoption, adjusted balance
Statement [Line Items]
Balance at beginning of fiscal year		0	0	(124,636)	[1]
Balance at beginning of fiscal year, adjusted		2,665,608	2,967,385	2,576,138
Balance at end of fiscal year			0	0
Accumulated other comprehensive income (loss)
Statement [Line Items]
Balance at beginning of fiscal year	[2]	440,112	318,114	(9,494)
Change during year	[2]	209,283	121,998	327,608
Balance at end of fiscal year	[2]	649,395	440,112	318,114
Treasury Stock
Statement [Line Items]
Balance at beginning of fiscal year		(8,342)	(7,124)	(6,415)
Purchases of treasury stock		(2,315)	(2,870)	(2,545)
Disposal of treasury stock		1,871	1,652	1,836
Balance at end of fiscal year		(8,786)	(8,342)	(7,124)
Parent
Statement [Line Items]
Balance at beginning of fiscal year		8,914,212	9,105,238
Balance at end of fiscal year		8,915,491	8,914,212	9,105,238
Noncontrolling Interest
Statement [Line Items]
Balance at beginning of fiscal year		528,019	582,919	663,259
Transactions between the MHFG Group and the noncontrolling interest shareholders		254,914	(44,651)	(300,371)
Dividends paid to noncontrolling interests		(21,732)	(18,095)	(15,753)
Net income attributable to noncontrolling interests		48,037	3,251	236,283
Other		405	4,595	(499)
Balance at end of fiscal year		¥ 809,643	¥ 528,019	¥ 582,919
[1]These amounts resulted from the adoption of ASU No.2016-13, “Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments” and subsequent amendments. See Note 1 “Basis of presentation and summary of significant accounting policies” for further details.[2]The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 16 “Accumulated other comprehensive income (loss), net of tax.”

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net income (loss)		¥ 34,028	¥ (101,471)	¥ 818,048
Less: Net income attributable to noncontrolling interests		48,037	3,251	236,283
Net income (loss) attributable to MHFG shareholders		(14,009)	(104,722)	581,765
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization		238,997	228,397	231,677
Provision (credit) for credit losses		93,753	214,408	112,776
Investment losses (gains)—net		(140,768)	75,340	(828,535)
Equity in losses (earnings) of equity method investees—net	[1]	26,999	(34,587)	(31,027)
Foreign exchange losses (gains)—net		439,767	517,989	207,400
Deferred income tax expense (benefit)		(143,842)	(255,365)	50,701
Net change in trading account assets		(4,031,782)	2,386,304	1,567,897
Net change in trading account liabilities		4,235,704	3,634,056	(1,984,509)
Net change in loans held for sale		(72,356)	(126,804)	30,250
Net change in accrued income		(179,772)	4,680	8,052
Net change in accrued expenses		259,428	2,783	(72,850)
Other—net		294,794	(1,044,392)	595,159
Net cash provided by operating activities		1,006,913	5,498,087	468,756
Cash flows from investing activities:
Proceeds from sales of Available-for-sale securities		35,864,487	36,330,397	28,041,466
Proceeds from sales of Equity securities (Note)	[2]	930,586	2,526,075	3,089,202
Proceeds from maturities of Available-for-sale securities		39,537,476	39,008,678	31,521,663
Proceeds from maturities of Held-to-maturity securities		227,711	178,955	116,060
Purchases of Available-for-sale securities		(68,223,956)	(80,478,884)	(69,491,642)
Purchases of Held-to-maturity securities		(677,508)	(714,794)	(134,660)
Purchases of Equity securities (Note)	[2]	(914,215)	(2,208,196)	(2,979,434)
Proceeds from sales of loans		492,933	2,046,573	1,847,102
Net change in loans		(2,615,468)	(1,397,302)	(1,502,445)
Net change in call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		1,790,227	(147,806)	6,906,483
Proceeds from sales of premises and equipment		9,813	18,720	13,664
Purchases of premises and equipment		(185,583)	(136,238)	(211,495)
Proceeds from sales of investments in subsidiaries (affecting the scope of consolidation)		2,872	50,699	218,259
Purchases of investments in subsidiaries (affecting the scope of consolidation)		(48,887)	(93,005)	(47,515)
Net cash provided by (used in) investing activities		6,190,488	(5,016,128)	(2,613,292)
Cash flows from financing activities:
Net change in deposits		5,834,904	3,589,567	4,394,481
Net change in call money and funds purchased, and payables under repurchase agreements and securities lending transactions		4,444,768	9,268	(962,754)
Net change in due to trust accounts		359,135	9,454	131,056
Net change in other short-term borrowings		(4,338,379)	(1,711,421)	4,085,165
Proceeds from issuance of long-term debt		4,701,954	3,004,293	2,568,730
Repayment of long-term debt		(2,985,756)	(2,715,054)	(1,511,050)
Proceeds from noncontrolling interests		36,924	101,755	236,868
Payments to noncontrolling interests		(58,811)	(80,493)	(37,928)
Proceeds from sales of treasury stock		1,615	874	854
Purchases of treasury stock		(2,314)	(1,927)	(1,849)
Purchases of treasury stock of subsidiaries		0	0	(5,414)
Dividends paid		(209,457)	(196,783)	(190,498)
Dividends paid to noncontrolling interests		(21,732)	(18,095)	(15,753)
Net cash provided by financing activities		7,762,851	1,991,438	8,691,908
Effect of exchange rate changes on cash and cash equivalents		857,754	966,796	235,610
Net increase in cash and cash equivalents		15,818,006	3,440,193	6,782,982
Cash and cash equivalents at beginning of fiscal year		52,174,289	48,734,096	41,951,114
Cash and cash equivalents at end of fiscal year		67,992,295	52,174,289	48,734,096
Supplemental disclosure of cash flow information:
Interest paid		2,030,281	274,530	497,422
Income taxes paid		133,370	164,408	216,996
Noncash investing activities:
Transfer of loans into loans held-for-sale		¥ 2,089	¥ 15,916	¥ 20,335
[1]These amounts are revenues from contracts that do not meet the scope of ASC 606.[2]Proceeds from sales of Equity securities as well as Purchases of Equity securities include cash activity related to Other investments, the amounts of which are not significant.

Basis of presentation and summa

Basis of presentation and summary of significant accounting policies	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Basis of presentation and summary of significant accounting policies	1. Basis of presentation and summary of significant accounting policies Basis of presentation Mizuho Financial Group, Inc. (“MHFG”) is a joint stock corporation with limited liability under the laws of Japan. MHFG is a holding company for Mizuho Bank, Ltd. (“MHBK”), Mizuho Trust & Banking Co., Ltd. (“MHTB”), Mizuho Securities Co., Ltd. (“MHSC”), Asset Management One Co., Ltd. (“Asset Management One”), and other subsidiaries. MHFG, through its subsidiaries (“the MHFG Group,” or “the Group”), provides domestic and international financial services in Japan and other countries. For a discussion of the Group’s segment information, see Note 30 “Business segment information.” MHFG and its domestic subsidiaries as well as its foreign subsidiaries maintain their accounting records in accordance with the accounting standards of Japan and those standards of the countries in which they are domiciled. Certain adjustments and reclassifications have been incorporated in the accompanying consolidated financial statements to conform them to the accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements are stated in Japanese yen, the currency of the country in which MHFG is incorporated and principally operates. The accompanying consolidated financial statements include the accounts of MHFG and its subsidiaries. MHFG’s fiscal year ends on March 31. MHFG’s subsidiaries fiscal year end is determined by each subsidiary. If the fiscal year end of a subsidiary has more than three months discrepancy from the MHFG’s fiscal year end, the subsidiary executes provisional financial closing. For those subsidiaries where the fiscal year end is not on March 31 and where the subsidiaries do not execute provisional financial close, the effect on the MHFG Group’s consolidated financial statements of all material events through the date of each of the periods presented in the consolidated financial statements has been considered for adjustment and/or disclosure. When determining whether to consolidate investee entities, the MHFG Group performs an analysis of the facts and circumstances of the particular relationships between the MHFG Group and the investee entities as well as the ownership of voting shares. The consolidated financial statements also include the accounts of VIEs for which MHFG or its subsidiaries have been determined to be the primary beneficiary in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 810, “Consolidation” (“ASC 810”). All significant intercompany transactions and balances have been eliminated upon consolidation. The MHFG Group accounts for investments in entities over which it has significant influence by using the equity method of accounting. These investments are included in Other investments and the Group’s proportionate share of income or loss is included in Equity in earnings (losses) of equity method investees—net. Certain comparative amounts for the prior period have been reclassified in order to conform to the current period’s presentation. Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts and related disclosures. Specific areas, among others, requiring the application of management’s estimates and judgment include assumptions pertaining to the allowance for credit losses, valuation of loans held-for-sale, valuation of deferred tax assets, valuation of derivative financial instruments, valuation of investments, valuation of certain long-term debt where the fair value option has been elected, valuation of pension and other employee benefits, and impairment of long-lived assets. During times of geopolitical unrest such as the situation in Russia and Ukraine and economic uncertainty such as elevated global inflation, estimates become more sensitive and it is reasonably possible that actual results could differ from estimates and assumptions made. Definition of cash and cash equivalents For purposes of the consolidated statements of cash flows, Cash and cash equivalents consists of Cash and due from banks and Interest-bearing deposits in other banks. Cash deposited with central banks that must be maintained to meet minimum regulatory requirements is classified as restricted cash and included in Cash and cash equivalents. See Note 8 “Pledged assets and collateral” for more information on restricted cash. Translation of foreign currency financial statements and foreign currency transactions Financial statements of overseas entities are prepared using the functional currency of each entity and translated into Japanese yen for consolidation purposes. Assets and liabilities are translated using the fiscal-year-end Foreign currency translation gains and losses related to the financial statements of overseas entities of the MHFG Group, net of related income tax effects, are credited or charged directly to Foreign currency translation adjustments, a component of Accumulated other comprehensive income (loss), net of tax (“AOCI”). The tax effects of gains and losses related to the foreign currency translation of financial statements of overseas entities are not recognized unless it is apparent that the temporary differences will reverse in the foreseeable future. Assets and liabilities of domestic and overseas entities denominated in foreign currencies are remeasured into the functional currency of the respective entity at the fiscal year-end Call loans and call money Call loans and call money represent lending/borrowing, primarily through the Japanese short-term money market, to/from other financial institutions such as banks, insurance companies, and securities brokerage houses. Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions Securities sold under agreements to repurchase (“repurchase agreements”), securities purchased under agreements to resell (“resale agreements”) and securities lending and borrowing transactions are accounted for as secured financing or lending transactions when control over the underlying securities is not deemed to be surrendered by the transferor. Otherwise, they are recorded as sales of securities with related forward repurchase commitments or purchases of securities with related forward resale commitments in accordance with ASC 860, “Transfers and Servicing” (“ASC 860”). Under resale agreements, securities borrowing and certain derivatives transactions, the MHFG Group receives collateral in the form of securities. In many cases, the MHFG Group is permitted to sell or repledge the securities obtained as collateral. Disclosures in respect of such collateral are presented in Note 8 “Pledged assets and collateral.” With respect to repurchase agreements, securities lending, and certain derivative transactions, counterparties may have the right to sell or repledge securities that the MHFG Group has pledged as collateral. The MHFG Group separately discloses these pledged securities in the consolidated balance sheets. The MHFG Group monitors credit exposure arising from resale agreements, repurchase agreements, securities borrowing and securities lending transactions on a regular basis, and additional collateral is obtained from or returned to counterparties, as appropriate. Trading securities and trading securities sold, not yet purchased Trading securities consist of securities and money market instruments that are bought and held principally for the purpose of reselling in the near term with the objective of generating profits on short-term fluctuations in price. Trading securities sold, not yet purchased, are securities and money market instruments sold to third parties that the MHFG Group does not own and is obligated to purchase at a later date to cover the short position. Trading securities and trading securities sold, not yet purchased, are recorded on the trade date. Trading securities and trading securities sold, not yet purchased, are recorded at fair value in the consolidated balance sheets in Trading account assets and Trading account liabilities with realized and unrealized gains and losses recorded on a trade date basis in Trading account gains (losses)—net in the consolidated statements of income. Interest and dividends on trading securities, including securities sold, not yet purchased, are recorded in Interest and dividend income or Interest expense on an accrual basis. Investments Debt securities that the MHFG Group has both the positive intent and ability to hold to maturity are classified as Held-to-maturity Available-for-sale At the end of each reporting period the MHFG Group performs a review to identify impaired available-for-sale available-for-sale first-in first-out Other investments include marketable and non-marketable non-marketable Derivative financial instruments Derivative financial instruments are bought and held principally for the purpose of market making for customers, proprietary trading in order to generate trading revenues and fee income, and also to manage the MHFG Group’s exposure to interest rate, credit and market risks related to asset and liability management. Such derivative financial instruments include interest rate, foreign currency, equity, commodity and credit default swap agreements, options, caps and floors, and financial futures and forward contracts. Derivatives bought and held for trading purposes are recorded in the consolidated balance sheets at fair value in Trading account assets and Trading account liabilities. The fair values of derivatives in a gain position and a loss position are reported as Trading account assets and Trading account liabilities, respectively. Derivatives used for asset and liability management include contracts that qualify for hedge accounting under ASC 815, “Derivatives and Hedging” (“ASC 815”). To be eligible for hedge accounting, derivative instruments must be highly effective in achieving offsetting changes in fair values or variable cash flows of the hedged items attributable to the particular risk being hedged. All qualifying hedging derivatives are valued at fair value and included in Trading account assets or Trading account liabilities. Derivatives that do not qualify for hedge accounting under ASC 815 are treated as trading positions and are accounted for as such. The fair value amounts recognized for all derivatives are presented on a gross basis and not offset against the amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under the master netting agreement with the same counterparty. The fair values of derivative financial instruments are determined based on quoted market prices or broker-dealer quotes, if available. If not available, the fair values are estimated using quoted market prices for similar instruments, option or binomial pricing models or a present value cash flow analysis, utilizing current observable market information, where available. In determining the fair values, the Group considers various factors such as exchange or over-the-counter Changes in the fair values of all derivatives are recorded in earnings, except for derivatives qualifying as net investment hedges under ASC 815 which are recorded in AOCI. The changes in the fair values of all derivatives relating to foreign currency exchange rates are included in Foreign exchange gains (losses)—net and Trading account gains (losses)—net. Other elements of the changes in the fair values, including interest rate, equity and credit related components, except these of certain credit derivatives hedging the credit risk in the corporate loan portfolio, are recognized in Trading account gains (losses)—net. The net gain (loss) resulting from changes in the fair values of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure related to its corporate loan portfolio is recorded in Other noninterest income (expenses). Certain financial and hybrid instruments often contain embedded derivative instruments that possess implicit or explicit contract terms similar to those of a derivative instrument. Such derivative instruments are required to be fair-valued separately from the host contracts if they meet the bifurcation criteria of an embedded derivative. Such criteria include that the entire instrument is not marked to market through earnings, the economic characteristics and risks of the embedded contract terms are not clearly and closely related to those of the host contract and the embedded contract terms would meet the definition of a derivative on a stand-alone basis. Loans Loans are generally carried at the principal amount adjusted for unearned income and deferred net nonrefundable loan fees and costs. Loan origination fees, net of certain direct origination costs, are deferred and recognized over the contractual life of the loan as an adjustment of yield using a method that approximates the interest method. Interest income on performing loans is accrued and credited to income as it is earned. Unearned income and discounts or premiums on purchased loans are deferred and recognized over the life of the loan using a method that approximates the interest method. Loans are considered nonaccrual when, based on current information and events, it is probable that the MHFG Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. Factors considered by management in determining if a loan is nonaccrual include delinquency status and the ability of the debtor to make payments of the principal and interest when due. Nonaccrual loans include loans past due for 90 days or more and restructured loans that meet the definition of a troubled debt restructuring (“TDR”) in accordance with ASC 310, “Receivables” (“ASC 310”). The majority of nonaccrual loans have no contractual delinquency due to interest reductions and/or postponement of principal and interest. In case loans are designated as nonaccrual loans, interest accruals and the amortization of net origination fees are suspended and capitalized interest is written off. Cash received on nonaccrual loans is accounted for as a reduction of the loan principal if the ultimate collectability of the principal amount is in doubt, otherwise, as interest income. Loans are not restored to accrual status until interest and principal payments are current and future payments are reasonably assured. Nonaccrual loans are restored to accrual loans and accrual status, when the MHFG Group determines that the borrower poses no concerns regarding current certainty of debt fulfillment. In general, such determination is made if the borrower qualifies for an obligor rating of E2 or above and is not classified as a special attention obligor. With respect to loans restructured in a TDR, in general, such loans are restored to accrual loans, and accrual status, when the borrower qualifies for an obligor rating of D or above. See Note 4 “Loans” for the definitions of obligor ratings. Loans that have been identified for sale are classified as loans held for sale within Other assets and are accounted for at the lower of cost or fair value on an individual loan basis. If management decides to retain certain loans held for sale for the foreseeable future or until maturity or payoff, such items are transferred to Loans at the lower of cost or fair value. Financial instruments—current expected credit losses (“CECL”) CECL established a single allowance framework for all financial assets measured at amortized cost and certain off-balance-sheet available-for-sale Allowance and provision (credit) for credit losses on loans Effective April 1, 2020, the allowance for credit losses on loans is established for current expected credit losses on the MHFG Group’s loan portfolio in accordance with ASC 326. Additionally, as of April 1, 2020, the Group did not elect the fair value option for financial assets measured at amortized cost basis. Prior to April 1, 2020, the allowance for credit losses on loans was established based on an incurred loss model in accordance with ASC 310 and ASC 450, “Contingencies” (“ASC 450”). The MHFG Group makes adjustments to the allowance for credit losses on loans through Provision (credit) for credit losses in the consolidated statements of income in each reporting period. Loan principal that management judges to be uncollectible, based on detailed loan reviews and a credit quality assessment, is charged off against the allowance for credit losses on loans. In general, the Group charges off loans when the Group determines that the obligor should be classified as substantially bankrupt or bankrupt. See Note 4 “Loans” for the definitions of obligor categories. Obligors in the retail portfolio segment are generally determined to be substantially bankrupt when they are past due for more than six months, and as for obligors in the corporate portfolio segment, the Group separately monitors the credit quality of each obligor without using time-based triggers. The MHFG Group maintains an appropriate allowance for credit losses on loans to represent management’s estimate of the expected credit losses in the Group’s loan portfolio. Management evaluates the appropriateness of the allowance for credit losses on loans semi-annually. The allowance considers expected credit losses over the remaining expected lives of the applicable instruments. The expected life of each instrument is determined by considering expected prepayments, contractual terms and cancellation features. The allowance for credit losses involves significant judgments on a number of matters including expectations of future economic conditions, assignment of obligor ratings, valuation of collateral, and the development of qualitative adjustments. When determining expected credit losses, a single forward-looking macroeconomic scenario is considered over a reasonable and supportable forecast period. This forward-looking macroeconomic scenario is in line with the scenario used for the Group’s business plan. If the scenario does not reflect a sudden change in economic conditions adequately, adjustments may be made to the scenario. After the forecast period, the Group reverts to long-term historical loss experience with a certain graduated transition period, to estimate losses over the remaining lives of financial assets measured at amortized cost and certain off-balance-sheet In terms of the internal risk ratings, for the corporate portfolio segment, the credit quality review process and the credit rating process serve as the basis for determining the allowance for credit losses on loans. Through such processes loans are categorized into groups to reflect the probability of default, whereby the MHFG Group’s management assesses the ability of borrowers to service their debt, taking into consideration current financial information, ability to generate cash, historical payment experience, analysis of relevant industry segments and current trends. For the retail portfolio segment, the different categories of past due status of loans are primarily utilized in the credit quality review and the credit rating processes as the basis for determining the allowance for credit losses on loans. In general, the MHFG Group estimates expected credit losses collectively on the loans in the case of normal and watch obligors, considering the risk associated with a particular pool and the probability that the exposures within the pool will deteriorate or default. The allowance for credit losses on nonaccrual loans generally includes the allowance for those loans that were individually evaluated for expected credit losses. See Note 4 “Loans” for the definitions of obligor categories and classification of nonaccrual loans. The estimation of expected credit losses that are evaluated collectively begins with a quantitative calculation that considers the likelihood of the borrower changing delinquency status or moving from one obligor category or rating to another. The quantitative calculation covers expected credit losses over an instrument’s expected life and is estimated by applying credit loss factors to the MHFG Group’s estimated exposure at default. The credit loss factors incorporate the probability of default as well as the loss given default based on the historical loss rates. To supplement the historical loss data for overseas obligors, external credit ratings such as S&P are also used to calculate the probability of default. The model and inputs used to determine credit losses on loans that are evaluated collectively are analyzed on a periodic basis by comparing the estimated values with the actual results subsequent to the balance sheet date. The MHFG Group divides its overall portfolio into domestic and foreign portfolios and categorizes the domestic portfolio into four portfolio segments according to their risk profiles: corporate, retail, sovereign, and banks and financial institutions. The corporate portfolio segment consists of loans originated primarily by MHBK and MHTB, and includes mainly business loans such as those used for working capital and capital expenditure, as well as loans for which the primary source of repayment of the obligation is income generated by the relevant assets such as project finance, asset finance and real estate finance. The corporate portfolio segment is divided into two classes based on their risk characteristics: large companies, and small and medium-sized The retail portfolio segment consists mainly of residential mortgage loans originated by MHBK, and it is divided into two classes based on their risk characteristics: housing loan and others. For the retail portfolio segment, the Japanese unemployment rate is applied as a key factor. As it pertains to TDRs in the retail portfolio segment, the restructuring itself, as well as subsequent payment defaults, if any, are considered in determining obligor categories. Expected credit loss estimates also include consideration of expected cash recoveries on loans previously charged-off, The allowance recorded for individually evaluated loans is based on (1) the present value of expected future cash flows, after considering the restructuring effect and subsequent payment default with respect to TDRs, discounted at the loan’s initial effective interest rate, (2) the loan’s observable market price, or (3) the fair value of the collateral if the loan is collateral dependent. The collateral that the MHFG Group obtains for loans consists primarily of real estate. In obtaining the collateral, the Group evaluates the fair value of the collateral and its legal enforceability. The Group also performs subsequent re-evaluations The MHFG Group’s methodology for determining the appropriate allowance for credit losses on loans also considers the imprecision inherent in the methodologies used. As a result, the amounts determined under the methodologies described above could be adjusted by management to consider the potential impact of other qualitative factors which include, but are not limited to, imprecision in macroeconomic scenario assumptions and emerging risks related to changes in the environment that are affecting specific portfolio segments including segments impacted by the Russia-Ukraine situation. Considering internal and external factors affecting the credit quality of the portfolio, the Group incorporated the estimated impact of the Russia-Ukraine situation, elevated global inflation and other factors contributing to economic uncertainty into the macroeconomic scenario by using assumptions such as the future outlook of the business environment for specific portfolio segments and the current forecast for the growth rate of gross domestic product. In terms of the Russia-Ukraine situation, considering the country risk arising from the continued sanctions against Russia and the downgrading of their credit rating, the MHFG Group incorporated the estimated impact of the Russia-Ukraine situation into the macroeconomic scenario used for determining the allowance for credit losses on loans. Allowance and provision (credit) for credit losses on off-balance-sheet The MHFG Group maintains an allowance for credit losses on off-balance-sheet off-balance-sheet off-balance-sheet Allowance and provision (credit) for credit losses on available-for-sale The MHFG Group performs periodic reviews to identify impaired securities in accordance with ASC 326. Available-for-sale available-for-sale available-for-sale available-for-sale available-for-sale Premises and equipment Premises and equipment are stated at historical cost, and depreciation and amortization are recorded over the estimated useful lives of the assets, except for leasehold improvements, which are amortized over the shorter of the estimated useful lives of the assets or the lease term. Depreciation and amortization are principally computed in accordance with the straight-line method with respect to buildings and leasehold improvements and in accordance with the declining-balance method with respect to other premises and equipment. The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20 Regular repairs and maintenance costs that do not extend the estimated useful life of an asset are charged to expense as incurred. Upon sale or disposition of premises and equipment, the cost and related accumulated depreciation or amortization are removed from the accounts, and any gains or losses on disposal are included in Gains on disposal of premises and equipment or Occupancy expenses. Impairment of long-lived assets The MHFG Group’s long-lived assets that are held for use are reviewed periodically for events or changes in circumstances that indicate possible impairment. The Group’s impairment review is based on an undiscounted cash flow analysis of a group of assets, combined with associated liabilities, at the lowest level for which identifiable cash flows exist. Impairment occurs when the carrying value of the asset group exceeds the future undiscounted cash flows that the asset group is expected to generate. When impairment is identified, the future cash flows are then discounted to determine the estimated fair value of the asset group and an impairment charge Software Internal and external costs incurred in connection with developing and obtaining software for internal use during the application development stage are capitalized. Such costs include salaries and benefits for employees directly involved with and who devote time to the project, to the extent such time is incurred directly on the internal use software project. The capitalization of software ceases when the software project has been substantially completed. The capitalized software is amortized on a straight-line basis over the estimated useful life, generally 5 to 10 years. Internal use software is reviewed for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. Goodwill Goodwill represents the excess of the total fair value of the acquired company, which consists of the consideration transferred, the fair value of any interest in the acquiree already held by the acquirer and the fair value of any noncontrolling interest in the acquiree over the fair value of net identifiable assets acquired at the date of acquisition in a business combination. The MHFG Group accounts for goodwill in accordance with ASC 350, “Intangibles—Goodwill and Other” (“ASC 350”). Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not amortized but is tested for impairment at least annually or more often if events or circumstances indicate there may be impairment. For both the annual and interim tests, the Group has the option to either (a) perform a quantitative impairment test or (b) first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, in which case the Group would perform the quantitative test. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value. The estimated fair value of the reporting units is derived based on valuation techniques that the Group believes market participants would use for each of the reporting units. The Group generally determines the estimated fair value by utilizing a discounted cash flow methodology or methodologies that incorporate price-to-book Intangible assets Intangible assets having definite useful lives are amortized over their estimated useful lives on either a straight-line basis or the method that reflects the pattern in which the economic benefits of the intangible assets are consumed. Intangible assets acquired in connection with the merger of MHSC and Shinko Securities Co., Ltd. (“Shinko”) and the integration of asset management functions of DIAM Co., Ltd. (“DIAM”), MHTB, Mizuho Asset Management Co., Ltd. (“MHAM”) and Shinko Asset Management Co., Ltd. (“Shinko Asset Management”) consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. Intangible assets having indefinite useful lives are not amortized and are subject to impairment tests. An impairment loss is recorded to the extent that the carrying amount of the indefinite-lived intangible asset exceeds its estimated fair value. For intangible assets subject to amortization, an impairment loss is recorded if the carrying amount is not recoverable and exceeds its estimated fair value. Leases The MHFG Group, as a lessee, recognizes liabilities to make lease payments and right-of-use non-lease right-of-use right-of-use right-of-use right-of-use Pension and other employee benefits MHFG and certain subsidiaries sponsor pension plans which provide defined benefits to retired employees and other postretirement benefit plans, including severance indemnities. Severance indemnities are amounts payable to eligible employees upon termination of employment and are payable as a lump sum. Periodic expense and accrued liabilities are computed based on the actuarial present value of benefits, net of investment returns expected from plan assets and their fair values at the balance sheet date. Net periodic expense is charged to Salaries and employee benefits. Net actuarial gains and losses that arise from differences between actual experience and assumptions are generally amortized over the average remaining service period of participating employees if they exceed the corridor, which is defined as the greater of 10% of plan assets or the projected benefit obligation. Stock-based compensation MHFG, MHBK, MHTB and MHSC have stock options, in the form of stock acquisition rights, for directors (excluding the outside directors) and executive officers of the respective companies (hereinafter referred to collectively as the “Directors”). In this plan (“the MHFG Group’s Stock Plan”), 100 shares of MHFG common stock shall be issued or transferred upon exercise of each of the stock acquisition rights. The exercise price is 1 yen per share. The contractual term of the stock acquisition rights is 20 years. A holder may exercise the stock acquisition rights only after the date on which such holder loses the status as a Director of MHFG, MHBK, MHTB or MHSC. In May 2015, the MHFG Group discontinued the stock option program. Thereafter, the MHFG Group has not issued any new stock options. MHFG, MHBK, MHTB and MHSC have a responsibility-based stock compensation program for Directors (“Stock Compensation I”) and a performance-based stock compensation program for Directors (“Stock Compensation II”). MHFG and certain consolidated subsidiaries introduced both responsibility-based and performance-based stock compensation program for Operating Officers (“Stock Benefit”) in July 2021. For these programs, the stock-based compensation cost is determined based on the fair value of MHFG’s common stock as of grant date. The liability related to the cash-based compensation cost is remeasured at each reporting date based on the fair value of MHFG’s common stock. For Stock Compensation I, as the program is effectively vested on the grant date, the stock-based compensation cost is recognized on the grant date. For Stock Compensation II, the stock-based compensation costs are recognized evenl

Issued accounting pronouncement

Issued accounting pronouncements	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Issued accounting pronouncements	2. Issued accounting pronouncements Adopted accounting pronouncements In March 2020, the FASB issued ASU No.2020-04, No.2020-04”). No.2021-01, No.2021-01”). No.2022-06, No.2022-06”). No.2020-04 ASU No.2021-01 No.2022-06 for Accounting pronouncements issued but not yet effective as of March 31, 2023 In March 2022, the FASB issued ASU No.2022-02, No.2022-02”). 310-40, 310-20-35-9 35-11 No.2022-02 No.2022-02

Investments

Investments	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Investments	3. Investments Available-for-sale held-to-maturity The amortized cost, net of allowance for credit losses, gross unrealized gains and losses, and fair value of available-for-sale held-to-maturity Amortized (4)(5) Gross gains Gross losses Fair value (in millions of yen) 2022 Available-for-sale Debt securities: Japanese government bonds 25,191,315 5,794 38,379 25,158,730 Japanese local government bonds 421,557 254 2,165 419,646 U.S. Treasury bonds and federal agency securities 381,653 — 8,444 373,209 Other foreign government bonds 1,338,295 220 2,578 1,335,937 Agency mortgage-backed securities (1) 452,830 1,695 3,985 450,540 Residential mortgage-backed securities 58,246 194 312 58,128 Commercial mortgage-backed securities 848,568 5,437 214 853,791 Japanese corporate bonds and other debt securities 2,222,670 14,212 1,705 2,235,177 Foreign corporate bonds and other debt securities (2) 787,263 2,490 1,021 788,732 Total 31,702,397 30,296 58,803 31,673,890 Held-to-maturity Debt securities: Japanese government bonds 479,980 5,101 — 485,081 Agency mortgage-backed securities (3) 1,039,075 24 58,604 980,495 Total 1,519,055 5,125 58,604 1,465,576 Amortized (4)(5) Gross gains Gross losses Fair value (in millions of yen) 2023 Available-for-sale Debt securities: Japanese government bonds 16,483,722 3,067 37,496 16,449,293 Japanese local government bonds 560,093 198 5,628 554,663 U.S. Treasury bonds and federal agency securities 382,990 — 7,289 375,701 Other foreign government bonds 1,309,473 661 2,261 1,307,873 Agency mortgage-backed securities (1) 532,364 1,140 11,307 522,197 Residential mortgage-backed securities 48,257 71 866 47,462 Commercial mortgage-backed securities 856,708 5,157 451 861,414 Japanese corporate bonds and other debt securities 2,100,733 13,024 4,538 2,109,219 Foreign corporate bonds and other debt securities (2) 1,005,209 2,319 1,581 1,005,947 Total 23,279,549 25,637 71,417 23,233,769 Held-to-maturity Debt securities: Japanese government bonds 799,305 2,171 1,028 800,448 Agency mortgage-backed securities (3) 1,250,802 403 136,545 1,114,660 Total 2,050,107 2,574 137,573 1,915,108 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥450,507 million and ¥33 million, respectively, at March 31, 2022, and ¥522,166 million and ¥31 million, respectively, at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. (2) Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥247,762 million at March 31, 2022, and ¥330,365 million at March 31, 2023. (3) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities. (4) Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale million at March 31, 2022, and ¥nil at March 31, 2023. (5) Accrued interest receivables are excluded from amortized cost, of which the amount were ¥4,702 million at March 31, 2022, and ¥5,637 million at March 31, 2023 and included in Accrued income. Contractual maturities The amortized cost, net of allowance for credit losses, and fair value of available-for-sale held-to-maturity Amortized cost Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 14,280,736 783,953 1,317,250 101,783 16,483,722 Japanese local government bonds 35,545 275,695 241,350 7,503 560,093 U.S. Treasury bonds and federal agency securities 382,990 — — — 382,990 Other foreign government bonds 1,027,119 279,985 1,186 1,183 1,309,473 Agency mortgage-backed securities — — 1,118 531,246 532,364 Residential mortgage-backed securities — — — 48,257 48,257 Commercial mortgage-backed securities 1,986 538,136 315,886 700 856,708 Japanese corporate bonds and other debt securities 412,207 1,155,415 240,446 292,665 2,100,733 Foreign corporate bonds and other debt securities 552,628 279,007 154,678 18,896 1,005,209 Total 16,693,211 3,312,191 2,271,914 1,002,233 23,279,549 Held-to-maturity Debt securities: Japanese government bonds 279,982 189,984 329,339 — 799,305 Agency mortgage-backed securities — — — 1,250,802 1,250,802 Total 279,982 189,984 329,339 1,250,802 2,050,107 Fair value Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 14,282,254 782,278 1,290,250 94,511 16,449,293 Japanese local government bonds 35,551 275,371 236,653 7,088 554,663 U.S. Treasury bonds and federal agency securities 375,701 — — — 375,701 Other foreign government bonds 1,026,121 279,384 1,186 1,182 1,307,873 Agency mortgage-backed securities — — 1,113 521,084 522,197 Residential mortgage-backed securities — — — 47,462 47,462 Commercial mortgage-backed securities 1,989 540,069 318,645 711 861,414 Japanese corporate bonds and other debt securities 412,157 1,154,386 238,775 303,901 2,109,219 Foreign corporate bonds and other debt securities 552,946 278,975 154,033 19,993 1,005,947 Total 16,686,719 3,310,463 2,240,655 995,932 23,233,769 Held-to-maturity Debt securities: Japanese government bonds 280,980 190,917 328,551 — 800,448 Agency mortgage-backed securities — — — 1,114,660 1,114,660 Total 280,980 190,917 328,551 1,114,660 1,915,108 Credit losses The MHFG Group recognized no material allowance for credit loss on available-for-sale available-for-sale available-for-sale held-to-maturity held-to-maturity and summary of significant accounting policies Continuous unrealized loss position The following table shows the gross unrealized losses, net of allowance for credit losses, and fair value of available-for-sale Less than 12 months 12 months or more Total Fair value Gross unrealized losses Fair value Gross unrealized losses Fair value Gross unrealized losses (in millions of yen) 2022 Available-for-sale Debt securities: Japanese government bonds 19,407,878 11,377 1,565,950 27,002 20,973,828 38,379 Japanese local government bonds 229,562 1,277 136,733 888 366,295 2,165 U.S. Treasury bonds and federal agency securities 321,073 7,209 41,555 1,235 362,628 8,444 Other foreign government bonds 729,134 2,178 71,647 400 800,781 2,578 Agency mortgage-backed securities (Note) 183,150 2,326 78,717 1,659 261,867 3,985 Residential mortgage-backed securities 9,221 11 17,193 301 26,414 312 Commercial mortgage-backed securities 58,815 185 13,939 29 72,754 214 Japanese corporate bonds and other debt securities 605,067 1,516 53,020 189 658,087 1,705 Foreign corporate bonds and other debt securities 302,569 692 53,338 329 355,907 1,021 Total 21,846,469 26,771 2,032,092 32,032 23,878,561 58,803 2023 Available-for-sale Debt securities: Japanese government bonds 3,706,134 11,369 1,419,222 26,127 5,125,356 37,496 Japanese local government bonds 146,484 1,596 322,224 4,032 468,708 5,628 U.S. Treasury bonds and federal agency securities 65,288 765 293,149 6,524 358,437 7,289 Other foreign government bonds 475,493 674 250,130 1,587 725,623 2,261 Agency mortgage-backed securities (Note) 142,776 2,361 238,858 8,946 381,634 11,307 Residential mortgage-backed securities 16,230 265 22,017 601 38,247 866 Commercial mortgage-backed securities 105,346 304 43,653 147 148,999 451 Japanese corporate bonds and other debt securities 1,177,725 3,775 635,289 763 1,813,014 4,538 Foreign corporate bonds and other debt securities 434,339 1,279 68,959 302 503,298 1,581 Total 6,269,815 22,388 3,293,501 49,029 9,563,316 71,417 Note: Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥261,867 million at March 31, 2022, and ¥381,634 million at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. At March 31, 2023, the MHFG Group did not intend to sell the debt securities in an unrealized loss position and it was not more likely than not that the Group would be required to sell them before the recovery of their amortized cost bases. For Japanese government bonds, U.S. Treasury bonds and federal agency securities and Agency mortgage-backed securities, their entire amortized cost bases are expected to be recovered since the unrealized losses had not resulted from credit deterioration, but primarily from changes in interest rates. For the debt securities other than those described above, except for the securities for which credit losses have been recognized in income, the Group determined that their entire amortized cost bases are expected to be recovered, after considering various factors such as the extent to which their fair values were below their amortized cost bases, the external and/or internal ratings and the present values of cash flows expected to be collected. Based on the aforementioned evaluation, except for the securities for which credit losses have been recognized in income, the Group determined that the debt securities in an unrealized loss position were not considered credit losses. Realized gains and losses The following table shows the realized gains and losses on sales of available-for-sale 2021 2022 2023 (in millions of yen) Gross realized gains 3,309 12,540 22,962 Gross realized losses (24,407 ) (40,077 ) (23,593 ) Net realized gains (losses) on sales of available-for-sale (21,098 ) (27,537 ) (631 ) Equity securities Equity securities include securities which have readily determinable fair values, securities which qualify for the practical expedient to estimate fair value using the net asset value per share (or its equivalent), and securities which are without readily determinable fair values. Equity securities which have readily determinable fair values mainly consist of common stock of Japanese listed companies. Equity securities which are measured based on the net asset value per share (or its equivalent) consist of private equity and real estate funds. Equity securities without readily determinable fair values include non-marketable Net gains and losses The following table shows the details of the net gains and losses on Equity securities for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Net gains (losses) recognized during the period on equity securities 850,567 (60,563 ) 135,601 Less: Net gains (losses) recognized during the period on equity securities sold during the period 82,969 17,000 29,561 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting 767,598 (77,563 ) 106,040 Equity securities without readily determinable fair values The following table shows carrying amounts of equity securities without readily determinable fair values, for which the measurement alternative is used, and cumulative amounts due to downward adjustments and impairments and upward adjustments, at March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Carrying amounts at the end of the period 186,146 207,407 207,743 Downward adjustments and impairments 5,087 6,519 5,345 Upward adjustments 9,216 11,623 13,015 The following table shows amounts recognized in earnings during the period due to downward adjustments and impairments and upward adjustments for equity securities without readily determinable fair values. 2021 2022 2023 (in millions of yen) Downward adjustments and impairments 3,084 2,626 1,291 Upward adjustments 404 2,459 1,459 The MHFG Group elected to measure all equity securities without readily determinable fair values, which do not qualify for the practical expedient to estimate fair value, using the measurement alternative, which is made on an instrument-by-instrument Other investments The following table summarizes the composition of Other investments at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Equity method investments 519,552 598,772 Investments held by consolidated investment companies and other 62,836 68,429 Total 582,388 667,201 Equity method investments Investments in investees over which the MHFG Group has the ability to exert significant influence are accounted for using the equity method of accounting. Such investments included marketable equity securities with carrying values of ¥255,336 million and ¥268,736 million, at March 31, 2022 and 2023, respectively. The aggregate market values of these marketable equity securities were ¥456,195 million and ¥503,171 million, respectively. The majority of aggregate market values of these marketable equity securities as of March 31, 2023 as of March 31, 2023 non-marketable , and Rakuten Securities, Inc. , 27.00% Investments held by consolidated investment companies The MHFG Group consolidates certain investment companies over which it has control through either ownership or other means. Investment companies are subject to specialized industry accounting which requires investments to be carried at fair value, with changes in fair value recorded in earnings. The MHFG Group maintains this specialized industry accounting for investments held by consolidated investment companies, which consist of marketable and non-marketable

Loans

Loans	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Loans	4. Loans Credit quality information In accordance with the MHFG Group’s credit risk management policies, the Group uses an internal rating system that consists of credit ratings for the corporate portfolio segment and pool allocations for the retail portfolio segment as the basis of its risk management infrastructure. Credit ratings consist of obligor ratings which represent the level of credit risk of the obligor, and transaction ratings which represent the ultimate possibility of losses expected on individual loans by taking into consideration various factors such as collateral or guarantees involved. In principle, obligor ratings are applied to all obligors except those to which pool allocations are applied, and are subject to regular review at least once a year as well as special review which is required whenever the obligor’s credit standing changes. Pool allocations are applied to small loans that are less than a specified amount by pooling customers and loans with similar risk characteristics, and the risk is assessed mainly based on past due status and managed according to such pools. The Group generally reviews the appropriateness and effectiveness of the approach to obligor ratings and pool allocations once a year in accordance with predetermined policies and procedures. The Group does not record expected credit losses for accrued interest receivables because uncollectible accrued interest is reversed through interest income in a timely manner in line with the Group’s nonaccrual and past due policies for loans. The amount of accrued interest The Group does not believe that its exposure to any particular geographic area and business sector results in a significant concentration of credit risk. The table below presents the MHFG Group’s definition of obligor ratings used by MHBK and MHTB, and equivalent obligor ratings are determined for the other subsidiaries: Obligor category (1) (2) Obligor rating Definition Normal A Obligors whose certainty of debt fulfillment is very high, hence their level of credit risk is very low. B Obligors whose certainty of debt fulfillment poses no problems for the foreseeable future, and their level of credit risk is low. C Obligors whose certainty of debt fulfillment and their level of credit risk pose no problems for the foreseeable future. D Obligors whose current certainty of debt fulfillment poses no problems, however, their resistance to future economic environmental changes is low. Watch E1 Obligors that require observation going forward because of either minor concerns regarding their financial position, or their somewhat weak or unstable business conditions. E2 Obligors that require special observation going forward because of problems with their borrowings such as reduced or suspended interest payments, problems with debt fulfillment such as failure to make principal or interest payments, or problems with their financial position as a result of their weak or unstable business conditions. Intensive control F Obligors that are not yet bankrupt but are in financial difficulties and are deemed likely to become bankrupt in the future because of insufficient progress in implementing their management improvement plans or other measures (including obligors that are receiving ongoing support from financial institutions). Substantially bankrupt G Obligors that have not yet become legally or formally bankrupt but are substantially insolvent because they are in serious financial difficulties and are deemed to be incapable of being restructured. Bankrupt H Obligors that have become legally or formally bankrupt. Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered nonaccrual. (2) The Group classifies loans to special attention, intensive control, substantially bankrupt and bankrupt obligors as nonaccrual loans. The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2022 and 2023: Term loans by origination year 2021 2020 2019 2018 2017 Prior to Revolving Loans Total (in billions of yen) 2022 Domestic: Corporate: Large companies: Normal obligors 12,236 6,641 5,049 4,535 1,679 3,379 7,155 40,674 Watch obligors excluding special attention obligors 146 69 71 66 40 51 128 571 Nonaccrual loans 61 101 201 45 136 77 178 799 Small and medium-sized Normal obligors 540 397 376 283 171 494 548 2,809 Watch obligors excluding special attention obligors 44 31 30 32 12 33 25 207 Nonaccrual loans 18 20 15 11 7 38 32 141 Retail: Housing Loan: Normal obligors 798 544 519 527 544 4,753 — 7,685 Watch obligors excluding special attention obligors 2 1 2 2 1 40 — 48 Nonaccrual loans 12 3 1 1 1 31 — 49 Others: Normal obligors 196 277 112 91 61 315 497 1,549 Watch obligors excluding special attention obligors 24 35 10 8 4 6 9 96 Nonaccrual loans 7 8 3 4 4 23 13 62 Sovereign: Normal obligors 938 106 89 109 55 352 2 1,651 Watch obligors excluding special attention obligors 4 4 1 — — — — 9 Nonaccrual loans — — — — — — — — Banks and other financial institutions: Normal obligors 46 24 132 211 — 144 125 682 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 15,072 8,261 6,611 5,925 2,715 9,736 8,712 57,032 Foreign: Corporate (4) Normal obligors 14,088 3,571 3,236 1,392 550 1,229 5,906 29,972 Watch obligors excluding special attention obligors 317 180 74 56 28 25 122 802 Nonaccrual loans 35 2 13 17 15 23 10 115 Retail: Normal obligors 2 2 2 1 1 3 — 11 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 279 7 33 15 174 3 75 586 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — 1 — — — — 1 Banks and other financial institutions: Normal obligors 1,003 254 151 225 12 1 120 1,766 Watch obligors excluding special attention obligors 5 — — — — — — 5 Nonaccrual loans 1 — — — — — — 1 Total foreign 15,730 4,016 3,510 1,706 780 1,284 6,233 33,259 Total 30,802 12,277 10,121 7,631 3,495 11,020 14,945 90,291 Term loans by origination year 2022 2021 2020 2019 2018 Prior to Revolving Loans Total (in billions of yen) 2023 Domestic: Corporate: Large companies: Normal obligors 12,277 5,993 5,384 3,994 3,065 3,670 7,517 41,900 Watch obligors excluding special attention obligors 109 46 50 58 59 33 130 485 Nonaccrual loans 153 35 61 134 99 159 339 980 Small and medium-sized Normal obligors 551 301 285 248 221 571 531 2,708 Watch obligors excluding special attention obligors 45 16 26 16 18 28 20 169 Nonaccrual loans 26 7 16 9 8 27 29 122 Retail: Housing Loan: Normal obligors 711 570 476 468 478 4,723 — 7,426 Watch obligors excluding special attention obligors 1 2 1 2 1 35 — 42 Nonaccrual loans 8 2 2 1 1 25 — 39 Others: Normal obligors 184 87 226 80 64 297 484 1,422 Watch obligors excluding special attention obligors 22 6 21 5 4 5 8 71 Nonaccrual loans 9 4 6 2 4 20 10 55 Sovereign: Normal obligors 1,217 54 90 91 75 328 1 1,856 Watch obligors excluding special attention obligors 8 2 — — — — — 10 Nonaccrual loans — — — — — — — — Banks and other financial institutions: Normal obligors 107 17 23 134 155 114 95 645 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 15,428 7,142 6,667 5,242 4,252 10,035 9,164 57,930 Foreign: Corporate (4) Normal obligors 15,317 3,891 2,142 1,954 1,024 1,312 6,731 32,371 Watch obligors excluding special attention obligors 228 101 192 72 43 50 58 744 Nonaccrual loans 31 19 13 18 11 32 11 135 Retail: Normal obligors 2 1 1 1 1 3 — 9 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 160 188 7 32 5 2 83 477 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — 1 — — — 1 Banks and other financial institutions: Normal obligors 1,536 265 169 91 19 4 404 2,488 Watch obligors excluding special attention obligors 8 4 4 5 — — — 21 Nonaccrual loans — — — — — — — — Total foreign 17,282 4,469 2,528 2,174 1,103 1,403 7,287 36,246 Total 32,710 11,611 9,195 7,416 5,355 11,438 16,451 94,176 Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered nonaccrual. (2) The primary component of the retail portfolio segment is housing loans to individuals which obligor category is classified based on past due status. The trigger to reclassify obligors from normal obligors to watch obligors excluding special attention obligors is when the past due status is more than 30 days. (3) There were no significant revolving line of credit arrangements that converted to term loans during the fiscal year ended March 31, 2022 and 2023. (4) Corporate of foreign include d were at Unearned income and deferred loan fees was ¥196 billion and ¥238 billion at March 31, 2022 and 2023, respectively. The Group uses, as a practical expedient, the fair value of the collateral when recording the net carrying amounts of loans and determining the allowance for credit losses of such loans, for which the repayment is expected to be provided substantially through the operation or sale of the collateral, when the borrower is experiencing financial difficulty based on the assessment as of the reporting date. As of March 31, 2023, collateral relating to these loans was primarily comprised of real estate. There were no significant changes in the extent to which collateral secures these loans during this fiscal year Nonaccrual loans The MHFG Group considers loans to be nonaccrual when it is probable that the Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. The Group classifies loans to special attention, intensive control, substantially bankrupt and bankrupt obligors as nonaccrual loans. There are no loans that are 90 days past due and still accruing. The Group does not have any loans to borrowers that cause management to have serious doubts as to the ability of such borrowers to comply with the present loan repayment terms for the periods presented other than those already designated as nonaccrual loans. The table below presents nonaccrual loans information at March 31, 2022 and 2023: Amortized cost (1) Interest income recognized (2) Nonaccrual loans with an allowance Nonaccrual loans without an allowance Total nonaccrual loans (in billions of yen) 2022 Domestic: Corporate: Large companies 784 16 800 9 Small and medium-sized 121 19 140 2 Retail: Housing Loan 27 22 49 1 Others 40 22 62 1 Total domestic 972 79 1,051 13 Foreign: Total foreign (3) 110 7 117 1 Total 1,082 86 1,168 14 2023 Domestic: Corporate: Large companies 961 19 980 16 Small and medium-sized 103 19 122 1 Retail: Housing Loan 22 17 39 1 Others 37 18 55 1 Total domestic 1,123 73 1,196 19 Foreign: Total foreign (3) 132 4 136 4 Total 1,255 77 1,332 23 Notes: (1) Amounts represent the outstanding balances of nonaccrual loans. The MHFG Group’s policy for placing loans in nonaccrual status corresponds to the Group’s definition of nonaccrual loans. (2) Amounts represent the amount of interest income on nonaccrual loans recognized on a cash basis and included in Interest income on loans in the consolidated statements of income. (3) The majority of total foreign consist of corporate. The remaining balance of nonaccrual loans that have been partially charged off, was ¥13,046 m m Troubled debt restructurings The MHFG Group considers a loan modification to be a TDR when, for economic or legal reasons related to the obligor’s financial difficulties, it grants a concession to the obligor that it would not otherwise consider. The Group considers the relevant obligor to be in financial difficulty generally when its obligor rating is E2 or below. The following table presents modified loans that were determined to be TDRs during the fiscal years ended March 31, 2022 and 2023: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in billions of yen) 2022 Domestic: Corporate: Large companies 6 23 612 Small and medium-sized — — 125 Retail: Housing Loan — — 8 Others — — 22 Total domestic 6 23 767 Foreign: Total foreign (2) — — 63 Total 6 23 830 2023 Domestic: Corporate: Large companies — 141 595 Small and medium-sized — — 106 Retail: Housing Loan — — 5 Others — — 19 Total domestic — 141 725 Foreign: Total foreign (2) — — 66 Total — 141 791 Notes: (1) Amounts represent the book values of loans immediately after the restructurings. (2) The majority of total foreign consist of corporate. Payment default is deemed to occur when the loan becomes three months past due or the obligor is downgraded to the category of substantially bankrupt or bankrupt. The following table presents payment defaults which occurred during the fiscal years ended March 31, 2022 and 2023 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment 2022 2023 (in billions of yen) Domestic: Corporate: Large companies 8 95 Small and medium-sized 3 1 Retail: Housing Loan 1 1 Others 1 1 Total domestic 13 98 Foreign: Total foreign 14 10 Total 27 108 Age analysis of past due loans The table below presents an analysis of the age of the amortized cost basis in loans that are past due at March 31, 2022 and 2023: 30-59 days past due 60-89 days past due 90 days or more past due Total past due Current Total (in billions of yen) 2022 Domestic: Corporate: Large companies — — 27 27 42,017 42,044 Small and medium-sized 1 1 10 12 3,145 3,157 Retail: Housing Loan 15 8 17 40 7,742 7,782 Others 5 1 11 17 1,690 1,707 Sovereign — — — — 1,660 1,660 Banks and other financial institutions — — — — 682 682 Total domestic 21 10 65 96 56,936 57,032 Foreign: Total foreign (Note) — — 29 29 33,230 33,259 Total 21 10 94 125 90,166 90,291 2023 Domestic: Corporate: Large companies — 3 28 31 43,334 43,365 Small and medium-sized — — 9 9 2,990 2,999 Retail: Housing Loan 14 8 13 35 7,472 7,507 Others 4 1 10 15 1,533 1,548 Sovereign — — — — 1,866 1,866 Banks and other financial institutions — — — — 645 645 Total domestic 18 12 60 90 57,840 57,930 Foreign: Total foreign (Note) — — 23 23 36,223 36,246 Total 18 12 83 113 94,063 94,176 Note: The majority of total foreign consist of corporate. Net losses on sales of loans Net losses on sales of loans were ¥8,172 m m m

Allowance for Credit Losses on

Allowance for Credit Losses on Loans	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Allowance for credit losses on loans	5. Allowance for credit losses on loans Changes in Allowance for credit losses on loans by portfolio segment for the fiscal years ended March 31, 2021, 2022 and 2023 are shown below: Domestic Corporate Retail Sovereign Banks and Foreign (2) Total (in millions of yen) 2021 Balance at beginning of fiscal year 305,458 23,219 88 1,514 110,576 440,855 April 1, 2020 adoption of CECL 63,500 74,014 79 705 17,457 155,755 Adjusted balance at beginning of fiscal year 368,958 97,233 167 2,219 128,033 596,610 Provision (credit) for credit losses on loans 143,766 (8,558 ) (99 ) (1,596 ) (20,737 ) 112,776 Charge-offs (33,625 ) (6,802 ) — — (38,374 ) (78,801 ) Recoveries 2,321 1,298 — — 10,316 13,935 Net charge-offs (31,304 ) (5,504 ) — — (28,058 ) (64,866 ) Others (1) — — — — 6,329 6,329 Balance at end of fiscal year 481,420 83,171 68 623 85,567 650,849 2022 Balance at beginning of fiscal year 481,420 83,171 68 623 85,567 650,849 Provision (credit) for credit losses on loans 144,998 (6,895 ) (6 ) (227 ) 49,729 187,599 Charge-offs (3) (32,530 ) (4,166 ) — — (23,144 ) (59,840 ) Recoveries 7,618 1,304 — — 9,832 18,754 Net charge-offs (24,912 ) (2,862 ) — — (13,312 ) (41,086 ) Others (1) — — — 42 12,413 12,455 Balance at end of fiscal year 601,506 73,414 62 438 134,397 809,817 2023 Balance at beginning of fiscal year 601,506 73,414 62 438 134,397 809,817 Provision (credit) for credit losses on loans 51,551 (5,413 ) (9 ) 432 44,287 90,848 Charge-offs (3) (153,014 ) (5,664 ) — — (68,772 ) (227,450 ) Recoveries 5,858 1,204 — — 3,414 10,476 Net charge-offs (147,156 ) (4,460 ) — — (65,358 ) (216,974 ) Others (1) — — — — 17,268 17,268 Balance at end of fiscal year 505,901 63,541 53 870 130,594 700,959 Notes: (1) Others includes primarily foreign exchange translation. (2) The majority of total foreign consist of corporate. (3) Charge-offs increased from ¥ 59,840 for the fiscal year ended March 31, 2022 227,450 million for the fiscal year ended March 31, 2023 due mainly to a debt waiver to a domestic corporate borrower .

Premises and equipment

Premises and equipment	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Premises and equipment	6. Premises and equipment Premises and equipment at March 31, 2022 and 2023 consist of the following: 2022 2023 (in millions of yen) Land 571,837 577,755 Buildings 737,440 703,655 Equipment and furniture 373,825 378,015 Leasehold improvements 208,820 204,835 Construction in progress 21,737 44,393 Software 1,373,035 1,366,445 Total 3,286,694 3,275,098 Less: Accumulated depreciation and amortization 1,582,627 1,621,210 Premises and equipment—net 1,704,067 1,653,888 Depreciation and amortization expense for premises and equipment for the fiscal years ended March 31, 2021, 2022 and 2023 was ¥223,164 million, ¥220,436 million and ¥231,291 million, respectively. Depreciation and amortization expense related to software was reported in General and administrative expenses, and all other depreciation and amortization expense was reported in Occupancy expenses. The MHFG Group recognized impairment losses of ¥7,101 million on premises and equipment for the fiscal year ended March 31, 2021, of which ¥3,872 million was recorded in General and administrative expenses and ¥3,229 million was recorded in Occupancy expenses. Such losses included ¥3,397 million of impairment losses related mainly to entity-wide software that is no longer to be used. In addition, ¥2,275 million of impairment losses were recognized on real estate used mainly for certain branches in Global Corporate Company or Retail & Business Banking Company. This real estate is either no longer being used or the carrying amount is not recoverable. The MHFG Group recognized impairment losses of ¥13,500 million on premises and equipment for the fiscal year ended March 31, 2022, of which ¥433 million was recorded in General and administrative expenses and ¥13,067 million was recorded in Occupancy expenses. Such losses included ¥12,976 million of impairment losses related mainly to real estate used for the entity-wide assets. This real estate is either no longer being used or the carrying amount is not recoverable. The amount of impairment losses on premises and equipment for the fiscal year ended March 31, 2023 was not significant.

Goodwill and intangible assets

Goodwill and intangible assets	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Goodwill and intangible assets	7. Goodwill and intangible assets Goodwill The changes in Goodwill during the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) Balance at beginning of fiscal year 92,997 92,695 92,695 Goodwill acquired — — 233 Impairment losses recognized (302 ) — — Balance at end of fiscal year 92,695 92,695 92,928 Gross amount of goodwill (Note) 167,552 161,993 163,209 Accumulated impairment losses 74,857 69,298 70,281 Note: Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not allocated to the reportable segments in Note 30 “Business segment information.” Intangible assets The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2022 and 2023: 2022 2023 Gross carrying amount Accumulated amortization Net carrying amount Gross carrying amount Accumulated amortization Net carrying amount (in millions of yen) Intangible assets subject to amortization: Customer relationships (Note) 126,979 87,277 39,702 130,124 94,777 35,347 Other 1,468 1,237 231 2,883 1,408 1,475 Total 128,447 88,514 39,933 133,007 96,185 36,822 Intangible assets not subject to amortization: Total 8,006 — 8,006 7,859 — 7,859 Total 136,453 88,514 47,939 140,866 96,185 44,681 Note: Customer relationships were mainly acquired in connection with the merger of MHSC and Shinko on May 7, 2009 and the integration among asset management companies on October 1, 2016. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information. For the fiscal years ended March 31, 2021, 2022 and 2023, the MHFG Group recognized ¥8,513 million, ¥7,961 million and ¥7,706 million, respectively, of amortization expense in respect of intangible assets, reported in Other noninterest expenses. The table below presents the estimated aggregate amortization expense in respect of intangible assets for the next five years: (in millions of yen) Fiscal year ending March 31: 2024 7,210 2025 6,698 2026 6,194 2027 5,564 2028 2,559

Pledged assets and collateral

Pledged assets and collateral	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Pledged assets and collateral	8. Pledged assets and collateral The following amounts, by balance sheet classification, have been pledged as collateral for 2022 2023 (in billions of yen) Interest-bearing deposits in other banks 75 92 Trading account assets 5,426 7,830 Investments 8,091 12,452 Loans 9,056 8,715 Other assets 3,023 2,059 Total 25,671 31,148 The associated liabilities collateralized by the above assets at March 31, 2022 and 2023 are summarized below: 2022 2023 (in billions of yen) Deposits 910 988 Payables under repurchase agreements 5,864 10,542 Payables under securities lending transactions 645 721 Other short-term borrowings 5,113 1,003 Long-term debt 542 2,173 Total 13,074 15,427 The Bank of Japan (“the BOJ”) requires private depository institutions to maintain a certain amount of funds as reserves in current accounts with the BOJ, based on average deposit balances and certain other factors. There are similar reserve deposit requirements for foreign branches and subsidiaries engaged in banking businesses in foreign countries. These amounts are deemed to be restricted cash. At March 31, 2022 and 2023, the deposit amounts maintained with the BOJ and foreign central banks, which were included in Cash and due from banks and Interest-bearing deposits in other banks, were ¥48,897 billion and ¥64,993 billion, respectively. These balances included the reserve funds required to be maintained by the MHFG Group, which amounted to ¥1,678 billion and ¥1,701 billion at March 31, 2022 and 2023, respectively. At March 31, 2022 and 2023, the MHFG Group had received collateral that can be sold or repledged, with a fair value of ¥16,632 billion and ¥15,529 billion, respectively, of which ¥14,865 billion and ¥13,379 billion, respectively, was sold and repledged. Such collateral was primarily obtained in connection with resale or securities borrowing agreements, and was generally used as collateral for repurchase or securities lending agreements, or to cover short sales. This collateral received isn’t recognized on balance sheet.

Deposits

Deposits	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Deposits	9. Deposits The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2023 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 18,355,950 6,056,971 24,412,921 Due after one year through two years 1,376,534 174,580 1,551,114 Due after two years through three years 976,153 500 976,653 Due after three years through four years 240,172 — 240,172 Due after four years through five years 314,567 — 314,567 Due after five years 219,492 — 219,492 Total 21,482,868 6,232,051 27,714,919 Foreign offices: Due in one year or less 22,436,741 7,185,063 29,621,804 Due after one year through two years 25,120 281,524 306,644 Due after two years through three years 15,999 89,710 105,709 Due after three years through four years 23,404 — 23,404 Due after four years through five years 160 — 160 Due after five years 1,421 — 1,421 Total 22,502,845 7,556,297 30,059,142 Total 43,985,713 13,788,348 57,774,061 The aggregate estimated amounts of time deposits and certificates of deposit that meet or exceed insurance limit issued by domestic and foreign offices at March 31, 2022 and 2023 are shown in the following table: 2022 2023 (in billions of yen) Domestic offices: Time deposits 10,437 13,977 Certificates of deposit 10,448 6,232 Total 20,885 20,209 Foreign offices: Time deposits 18,505 22,503 Certificates of deposit 6,421 7,556 Total 24,926 30,059 The aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances at March 31, 2022 and 2023 was ¥585 billion and ¥586 billion, respectively.

Due to trust accounts

Due to trust accounts	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Due to trust accounts	10. Due to trust accounts MHTB holds assets on behalf of its customers in an agent, fiduciary or trust capacity. Such trust account assets are not the MHFG Group’s proprietary assets and are managed and accounted for separately. However, the cash in individual trust accounts is often placed with MHTB for the customers’ short-term investment needs. These amounts which MHTB owes to the trust accounts are recorded as Due to trust accounts.

Short-term borrowings and long-

Short-term borrowings and long-term debt	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Short-term borrowings and long-term debt	11. Short-term borrowings and long-term debt Short-term borrowings Short-term borrowings consist of Due to trust accounts, Call money and funds purchased, Payables under repurchase agreements and securities lending transactions, and Other short-term borrowings. Details of Other short-term borrowings at March 31, 2022 and 2023 are as follows: 2022 2023 (in millions of yen) Short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) 46,668 41,142 Commercial paper and short-term notes issued by MHFG’s subsidiaries (1) (2) 2,266,360 2,218,111 Borrowings from the Bank of Japan 5,105,225 876,036 Other 148,518 262,040 Total 7,566,771 3,397,329 Notes: (1) Short-term notes are issued under the laws of Japan in the form of commercial paper. (2) The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥1,775,860 million and ¥490,500 million, respectively, at March 31, 2022, and ¥1,782,111 million and ¥436,000 million, respectively, at March 31, 2023. Long-term debt Long-term debt with original maturities of more than one year at March 31, 2022 and 2023 is comprised of the following: 2022 2023 (in millions of yen) Obligations unde 4,621 6,863 Loan participation borrowings 220,312 245,176 Senior borrowings and bonds 8,600,493 11,245,475 Subordinated borrowings and bonds 3,752,790 3,395,509 Total 12,578,216 14,893,023 The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2022 2023 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-6.20 Apr.2023 Jun.2051 1,032,194 2,819,085 fixed rate denominated in U.S. dollars 0.00-5.75 Apr.2023 Mar.2048 3,581,901 3,692,271 fixed rate denominated in other currencies 0.00-5.92 Apr.2023 May.2041 1,223,991 1,948,714 floating rate denominated in Japanese yen 0.00-25.00 Apr.2023 Sep.2081 582,430 569,173 floating rate denominated in U.S. dollars 0.00-32.80 Apr.2023 Feb.2068 2,001,616 2,058,714 floating rate denominated in other currencies 0.10-12.00 Apr.2023 Sep.2041 178,361 157,518 Total 8,600,493 11,245,475 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.39-4.26 Jun.2023 Perpetual 3,171,343 2,961,504 fixed rate denominated in U.S. dollars 2.56-4.70 Mar.2024 Sep.2031 581,447 434,005 Total 3,752,790 3,395,509 Total 12,353,283 14,640,984 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2023. (2) Maturity information disclosed is the range of maturities at March 31, 2023. (3) None of the long-term debt issuances above are convertible to common stock. (4) Certain debt agreements permit the MHFG Group to redeem the related debt, in whole or in part, prior to maturity at the MHFG Group’s option on terms specified in the respective agreements. The following is a summary of contractual maturities of long-term debt subsequent to March 31, 2023: (in millions of yen) Fiscal year ending March 31: 2024 1,177,938 2025 3,757,328 2026 702,968 2027 1,428,227 2028 1,291,313 2029 and thereafter 6,535,249 Total 14,893,023

Other assets and liabilities

Other assets and liabilities	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Other assets and liabilities	12. Other assets and liabilities The following table sets forth the details of other assets and liabilities at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions 3,049,874 4,469,286 Other 557,842 468,344 Collateral pledged: Collateral pledged for derivative transactions 1,549,483 988,881 Margins provided for futures contracts 466,531 183,747 Other 1,006,849 890,350 Prepaid pension cost 762,147 768,998 Right-of-use 570,171 549,668 Security deposits 91,766 83,343 Loans held for sale 156,639 228,995 Other (1) 775,940 1,069,348 Total 8,987,242 9,700,960 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions 1,406,965 1,799,116 Other 494,538 527,493 Guaranteed trust principal (2) 810,776 817,448 Lease liabilities 593,339 571,087 Collateral accepted: Collateral accepted for derivative transactions 1,075,591 1,008,083 Margins accepted for futures contracts 327,883 81,925 Unearned income 113,181 112,077 Other 1,437,949 1,399,466 Total 6,260,222 6,316,695 Notes: (1) As of March 31, 2023, the MHFG Group included premises and equipment classified as held for sale in Other. (2) Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 23 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred stock

Preferred stock	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Preferred Stock	13. Preferred stock The composition of preferred stock at March 31, 2021, 2022 and 2023 is as follows: 2021 2022 2023 Class of stock Authorized Issued Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 90,000,000 — 90,000,000 — 90,000,000 — Class XV preferred stock 90,000,000 — 90,000,000 — 90,000,000 — Class XVI preferred stock 150,000,000 — 150,000,000 — 150,000,000 — Holders or registered pledgees of preferred stock are entitled to receive annual dividends, and distribution of residual assets of MHFG as set out above at the liquidation value per share, prior to holders of common stock but pari passu among themselves. MHFG may pay up to one-half There was no change in balance of the preferred stock in the

Common stock

Common stock	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Common stock	14. Common stock The following table shows the changes in the number of issued shares of common stock during the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (shares) Balance at beginning of fiscal year 2,539,249,894 2,539,249,894 2,539,249,894 Issuance of new shares of common stock due to exercise of stock acquisition rights — — — Balance at end of fiscal year 2,539,249,894 2,539,249,894 2,539,249,894

Dividends

Dividends	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Dividends	15. Dividends The amount available for dividends under Japan’s Companies Act is non-consolidated period-end Pursuant to the Companies Act, in making a distribution of retained earnings, an entity must set aside in its legal reserve an amount equal to one-tenth of the amount of retained earnings so distributed, until its legal reserve reaches one-quarter of its capital stock. MHFG’s legal reserve at March 31, 2023 was ¥1,201,010 million, of which ¥1,196,660 million was included in capital surplus and ¥4,350 million in retained earnings. In addition to the provision that requires an appropriation for the legal reserve, the Companies Act and Japan’s Banking Act impose certain limitations on the amount available for dividends. Under the Companies Act, MHFG’s maximum amount available for dividends, at March 31, 2023, was ¥2,203,318 million, based on the amount recorded in MHFG’s general books of account under Japanese GAAP. Under the Banking Act and related regulations, MHFG has to meet the minimum capital adequacy requirements. Distributions of retained earnings, which are otherwise distributable to shareholders, are restricted in order to maintain the minimum capital requirements. See Note 17 “Regulatory matters” for further discussion of regulatory capital requirements. Payment of dividends on shares of common stock is also subject to the prior payment of dividends on shares of preferred stock, if any are outstanding.

Accumulated other comprehensive

Accumulated other comprehensive income (loss), net of tax	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Accumulated other comprehensive income (loss), net of tax	16. Accumulated other comprehensive income (loss), net of tax Changes in each component of AOCI for the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) AOCI, balance at beginning of fiscal year (9,494 ) 318,114 440,112 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year (19,592 ) (8,173 ) (25,046 ) Unrealized holding gains (losses) during year (4,911 ) (35,922 ) (7,472 ) Less: reclassification adjustments for losses (gains) included in net income 16,330 19,049 1,434 Change during year 11,419 (16,873 ) (6,038 ) Balance at end of fiscal year (8,173 ) (25,046 ) (31,084 ) Foreign currency translation adjustments: Balance at beginning of fiscal year (109,872 ) (86,873 ) 94,104 Foreign currency translation adjustments during year 22,704 181,722 133,556 Less: reclassification adjustments for losses (gains) included in net income 295 (745 ) — Change during year 22,999 180,977 133,556 Balance at end of fiscal year (86,873 ) 94,104 227,660 Defined benefit plan adjustments: Balance at beginning of fiscal year 69,455 397,153 355,355 Unrealized gains (losses) during year 331,668 (22,825 ) 86,326 Less: reclassification adjustments for losses (gains) included in net income (3,970 ) (18,973 ) (18,004 ) Change during year 327,698 (41,798 ) 68,322 Balance at end of fiscal year 397,153 355,355 423,677 Own credit risk adjustments Balance at beginning of fiscal year 50,515 16,007 15,699 Unrealized gains (losses) during year (30,345 ) (858 ) 12,688 Less: reclassification adjustments for losses (gains) included in net income (4,163 ) 550 755 Change during year (34,508 ) (308 ) 13,443 Balance at end of fiscal year 16,007 15,699 29,142 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 327,608 121,998 209,283 AOCI, balance at end of fiscal year 318,114 440,112 649,395 The following table shows the amounts reclassified out of AOCI into net income during the fiscal year ended March 31, 2023: Before tax (1) Tax effect (2) Net of tax before allocation to noncontrolling interests Net of tax attributable to noncontrolling interests (2) Net of tax attributable to MHFG shareholders (in millions of yen) Amounts reclassified out of AOCI into net Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale (1,739 ) 305 (1,434 ) — (1,434 ) Investment gains (losses)—net Other noninterest income Defined benefit plan adjustments 25,840 (7,848 ) 17,992 12 18,004 Salaries and employee Own credit risk adjustments (1,089 ) 334 (755 ) — (755 ) Other noninterest income Total 23,012 (7,209 ) 15,803 12 15,815 Notes: (1) The financial statement line item in which the amounts in the before tax column are reported in the consolidated statements of income is listed to the right of the table. (2) The financial statement line items in which the amounts in the tax effect and the net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense (benefit) and Net income (loss), respectively.

Regulatory matters

Regulatory matters	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Regulatory matters	17. Regulatory matters Regulatory capital requirements MHFG, MHBK, and MHTB are subject to regulatory capital requirements supervised by the Financial Services Agency in accordance with the provisions of Japan’s Banking Act and related regulations. Certain foreign banking subsidiaries are subject to regulation and control by local supervisory authorities, including central banks. Failure to meet minimum capital requirements may initiate certain mandatory actions by regulators that, if undertaken, could have a direct material effect on the MHFG Group’s consolidated financial condition and results of operations. The capital adequacy guidelines applicable to Japanese banks and bank holding companies with international operations supervised by the Financial Services Agency closely follow the risk-adjusted approach proposed by the Bank for International Settlements and are intended to further strengthen the soundness and stability of Japanese banks. In December 2010, Basel Committee on Banking Supervision (“BCBS”) issued the Basel III rules text, which builds on the International Convergence of Capital Measurement and Capital Standards document (“Basel II”), to strengthen the regulation, supervision and risk management of the banking sector. Basel III rules text presents the details of global regulatory standards on bank capital adequacy and liquidity. The rules text sets out higher and better-quality capital, better risk coverage, introduction of a leverage ratio as a backstop to the risk-based requirement, measures to promote the build-up The Financial Services Agency’s capital adequacy guidelines became effective from March 31, 2013, which generally reflect the rules in the Basel III rules text that have been applied from January 1, 2013. There are three primary regulatory capital ratios used to assess capital adequacy: Common Equity Tier 1, Tier 1 and Total risk-based capital ratios. The ratios are comprised of Common Equity Tier 1 capital, Tier 1 capital (Common Equity Tier 1 capital and Additional Tier 1 capital) and total risk-based capital (Tier 1 and Tier 2 capital) divided by risk-weighted assets. Common Equity Tier 1 capital primarily consists of common stock, capital surplus, retained earnings and AOCI. Regulatory adjustments including certain intangible fixed assets, such as goodwill, and defined-benefit pension fund assets will be deducted from Common Equity Tier 1. Additional Tier 1 capital generally consists of Basel III compliant preferred securities and other capital that meets Tier 1 requirements under Basel II standards, net of regulatory adjustments. Tier 2 capital generally consists of Basel III compliant deferred obligations, such as subordinated debts, capital that meets Tier 2 requirements under Basel II standards, certain allowances for credit losses and noncontrolling interests in subsidiaries’ Tier 2 instruments. Under the revised guidelines, the minimum capital adequacy ratio is 8% on both a consolidated and non-consolidated In November 2015, the Financial Services Agency published the revised capital adequacy guidelines and related ordinances to introduce the capital buffer requirements under the Basel III rules for Japanese banks and bank holding companies with international operations, which include the capital conservation buffer, the countercyclical capital buffer and the additional loss absorbency requirements for (“G-SIBs”) (“D-SIBs”). G-SIBs D-SIBs build-up G-SIB D-SIB, Leverage ratio The leverage ratio framework is critical and complementary to the risk-based capital framework that will help ensure broad and adequate capture of both on- off-balance Basel III’s leverage ratio is defined as the capital measure (numerator) divided by the exposure measure (denominator) and is expressed as a percentage. The capital measure for the leverage ratio is the Tier 1 capital of the risk-based capital framework, and the exposure measure is the sum of the on-balance off-balance In non-consolidated The leverage ratio buffer requirement for G-SIBs G-SIBs In June 2020, in coordination with the monetary policy of the Bank of Japan in response to the impact of COVID-19, COVID-19. The capital requirements and regulatory adjustments are being phased in over a transitional period as follows: March 2022 March 2023 March 2024 March 2025 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % Capital conservation buffer 2.5 % 2.5 % 2.5 % 2.5 % Countercyclical capital buffer (1) 0.01 % 0.06 % 0.06 % 0.06 % Additional loss absorbency requirements for G-SIBs D-SIBs (2) 1.0 % 1.0 % 1.0 % 1.0 % Minimum Leverage Ratio 3.0 % 3.5 % (3) 3.5 % (3) 3.7 % (3) Notes: (1) Figures assume that the countercyclical capital buffer will continue to be 0.06% after March 2024. (2) Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB (3) This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB If the capital adequacy ratio and leverage ratio of a financial institution falls below the required level, the Financial Services Agency may, depending upon the extent of capital deterioration, take certain corrective action, including requiring the financial institution to submit an improvement plan to strengthen its capital base, reduce its total assets, restrict its business operations or other actions that could have a material effect on its financial condition and results of operations. Capital adequacy ratios and leverage ratios of MHFG, MHBK, and MHTB as of March 31, 2022 and 2023 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: 2022 2023 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (1) 5,184 8.01 5,676 8.06 Actual 8,067 12.46 8,315 11.80 Tier 1 capital: Required (1) 6,155 9.51 6,733 9.56 Actual 9,713 15.00 9,803 13.91 Total risk-based capital: Required (1) 7,450 11.51 8,142 11.56 Actual 11,351 17.53 11,306 16.05 Leverage Ratio (2) Required 6,389 3.00 7,680 3.50 (3) Actual 9,713 4.56 9,803 4.46 MHBK: Common Equity Tier 1 capital: Required 2,683 4.50 2,941 4.50 Actual 6,968 11.68 6,873 10.51 Tier 1 capital: Required 3,578 6.00 3,922 6.00 Actual 8,604 14.42 8,356 12.78 Total risk-based capital: Required 4,771 8.00 5,229 8.00 Actual 10,150 17.02 9,769 14.94 Leverage Ratio (2) Required 5,971 3.00 6,216 3.00 Actual 8,604 4.32 8,356 4.03 MHTB: Common Equity Tier 1 capital: Required 79 4.50 77 4.50 Actual 442 25.18 444 25.94 Tier 1 capital: Required 105 6.00 102 6.00 Actual 442 25.18 444 25.94 Total risk-based capital: Required 140 8.00 137 8.00 Actual 442 25.18 444 25.95 Leverage Ratio (2) Required 130 3.00 125 3.00 Actual 442 10.20 444 10.61 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,528 4.50 2,751 4.50 Actual 6,293 11.20 5,981 9.78 Tier 1 capital: Required 3,370 6.00 3,668 6.00 Actual 7,919 14.09 7,450 12.18 Total risk-based capital: Required 4,494 8.00 4,891 8.00 Actual 9,483 16.88 8,853 14.48 Leverage Ratio (2) Required 5,570 3.00 5,767 3.00 Actual 7,919 4.26 7,450 3.87 2022 2023 Amount Ratio Amount Ratio (in billions of yen, except percentages) MHTB: Common Equity Tier 1 capital: Required 78 4.50 76 4.50 Actual 425 24.40 425 25.10 Tier 1 capital: Required 104 6.00 101 6.00 Actual 425 24.40 425 25.10 Total risk-based capital: Required 139 8.00 135 8.00 Actual 425 24.40 425 25.11 Leverage Ratio (2) Required 126 3.00 122 3.00 Actual 425 10.09 425 10.44 Notes: (1) The required ratios disclosed above, at March 31, 2022, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01% and the additional loss absorbency requirements for G-SIBs D-SIBs %. The required ratios disclosed above, at March 31, 2023, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.06% and the additional loss absorbency requirements for G-SIBs and D-SIBs of 1.0%. These are all in addition to the regulatory minima. The respective required amounts are determined by applying the ratios to the sum of the risk weighted assets and certain other risk amounts. (2) The required and actual amounts disclosed above at March 31, 2022 and 2023 exclude amounts of deposits to the Bank of Japan. (3) The required ratio disclosed above, at March 31, 2023, includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB under the finalized Basel III reforms. MHFG’s securities subsidiary in Japan is also subject to the capital adequacy requirement under Japan’s Financial Instruments and Exchange Act. Under this requirement, securities firms must maintain a minimum capital adequacy ratio of 120% calculated as a percentage of capital accounts less certain assets, as calculated using Japanese GAAP figures, against amounts equivalent to market, counterparty, and basic risks. Specific guidelines are issued as a ministerial ordinance that details the definition of essential components of the capital ratios, including capital, disallowed assets and risks, and related measures. Failure to maintain a minimum capital ratio will trigger mandatory regulatory actions. A capital ratio of less than 140% will call for regulatory reporting and a capital ratio of less than 100% may lead to a temporary suspension of all or part of the business operations and further, to the cancellation of the license to act as a securities broker and dealer. Management believes, as of each latest balance sheet date, that MHFG, MHBK, MHTB, and their securities subsidiary in Japan and foreign banking subsidiaries were in compliance with all capital adequacy requirements to Business improvement orders MHFG and MHBK received business improvement orders dated November 26, 2021 from the Financial Services Agency of 52-33

Earnings per common share

Earnings per common share	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Earnings per common share	18. Earnings per common share The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Net income (loss): Net income (loss) attributable to MHFG common shareholders 581,765 (104,722 ) (14,009 ) Effect of dilutive securities — — — Net income (loss) attributable to common shareholders after assumed conversions 581,765 (104,722 ) (14,009 ) 2021 2022 2023 (thousands of shares) Shares: Weighted average common shares outstanding 2,537,513 2,537,051 2,536,596 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 89 — — Weighted average common shares after assumed conversions 2,537,602 2,537,051 2,536,596 2021 2022 2023 (in yen) Earnings per common share: Basic net income (loss) per common share 229.27 (41.28 ) (5.52 ) Diluted net income (loss) per common share (Note) 229.26 (41.28 ) (5.52 ) Note: For the fiscal years ended March 31, 2021, 2022 and 2023, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects. In addition, for the fiscal years ended March 31, 2022 and 2023, the computation of diluted earnings per common share did not assume exercise of stock options, as the effect of such exercise would be antidilutive due to net loss.

Income taxes

Income taxes	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Income taxes	19. Income taxes Income tax expense (benefit) The following table presents the components of Income tax expense (benefit) for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Current: Domestic 81,023 42,401 22,015 Foreign 78,992 71,947 156,969 Total current tax expense 160,015 114,348 178,984 Deferred: Domestic 55,927 (256,093 ) (146,721 ) Foreign (5,226 ) 728 2,879 Total deferred tax expense (benefit) 50,701 (255,365 ) (143,842 ) Total income tax expense (benefit) 210,716 (141,017 ) 35,142 The preceding table does not reflect the tax effects of items recorded directly in Equity for the fiscal years ended March 31, 2021, 2022 and 2023. The detailed amounts recorded directly in Equity are as follows: 2021 2022 2023 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) (2,810 ) (16,489 ) (4,276 ) Less: reclassification adjustments 7,195 8,504 305 Total 4,385 (7,985 ) (3,971 ) Defined benefit plan adjustments: Unrealized gains (losses) 143,653 (9,020 ) 37,661 Less: reclassification adjustments (1,424 ) (7,748 ) (7,848 ) Total 142,229 (16,768 ) 29,813 Own credit risk adjustments: Unrealized gains (losses) 919 1,745 5,630 Less: reclassification adjustments (1,911 ) 271 334 Total (992 ) 2,016 5,964 Total tax effect before allocation to noncontrolling interests 145,622 (22,737 ) 31,806 Reconciliation of Income tax expense (benefit) The following table shows a reconciliation of Income tax expense at the effective statutory tax rate to the actual income tax expense for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 Effective statutory tax rate 30.62 % 30.62 % 30.62 % Income not subject to tax (0.72 ) 4.21 (14.23 ) Expenses not deductible for tax purposes 0.07 (0.34 ) 1.63 Tax rate differentials of subsidiaries (0.90 ) 3.31 (12.95 ) Change in valuation allowance (3.83 ) (6.68 ) (2) (5.95 ) Change in undistributed earnings of subsidiaries 0.34 (2.22 ) 8.32 Noncontrolling interest income (loss) of consolidated VIEs (6.83 ) (2.10 ) (15.48 ) Effect of enacted change in tax rates (0.02 ) 0.01 (0.05 ) Reversal of outside basis differences — 50.59 (2) — Foreign tax credit and payments 0.16 (16.59 ) 55.14 Income excluded from taxable income of enterprise tax (0.49 ) 2.86 (14.96 ) Controlled foreign company rules 0.71 (1.66 ) 2.68 Other 1.37 (3.86 ) 16.04 Effective income tax rate 20.48 % 58.15 % 50.81 % Notes: (1) The presentation of the table is changed from from (2) These amounts for the fiscal year ended March 31, 2022 mainly represent the reversal of an outside basis difference related to the share buyback conducted by MHSC in response to improving the capital position and aligning to the MHFG Group’s capital policy and the related increase in the valuation allowance. Deferred tax assets and liabilities The components of net deferred tax assets at March 31, 2022 and 2023 are as follows: 2022 2023 (in millions of yen) Deferred tax assets: Allowance for credit losses 292,277 270,423 Lease liabilities 183,537 176,304 Trading securities 118,242 173,793 Derivative financial instruments 52,321 161,141 Premises and equipment 65,051 53,531 Available-for-sale 8,313 13,020 Net operating loss carryforwards (1) (2) 183,410 168,387 Other 223,564 255,557 1,126,715 1,272,156 Valuation allowance (1)(2) (163,164 ) (198,800 ) Deferred tax assets, net of valuation allowance 963,551 1,073,356 Deferred tax liabilities: Investments 213,398 264,147 Prepaid pension cost and accrued pension liabilities 221,256 224,173 Right-of-use 176,591 169,353 Other 104,020 54,515 Deferred tax liabilities 715,265 712,188 Net deferred tax assets 248,286 361,168 Notes: (1) The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income. (2) The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income. Deferred tax assets and deferred tax liabilities within the same tax jurisdiction have been netted for presentation purposes in the consolidated balance sheets. As of March 31, 2023, the accumulated amount of undistributed earnings that will be indefinitely reinvested and the unrecognized deferred tax liabilities related to such subsidiaries are approximately ¥349 billion and ¥36 billion, respectively. The following table and accompanying footnotes provide a breakdown of deferred tax assets and the valuation allowance recognized in respect of net operating loss carryforwards by tax jurisdiction and by year of expiration as of March 31, 2022 and 2023: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2022 Japan (1) 106 (77 ) 29 The United States 1 — 1 The United Kingdom (2) 75 (75 ) — Others 1 — 1 Total 183 (152 ) 31 2023 Japan (3) 89 (75 ) 14 The United States 1 — 1 The United Kingdom (2) 77 (77 ) — Others 1 — 1 Total 168 (152 ) 16 Notes: (1) ¥74 billion of the Japan deferred tax assets of ¥106 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥27 billion of the Japan deferred tax assets of ¥106 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes. (3) ¥49 billion of the Japan deferred tax assets of ¥89 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥25 billion of the Japan deferred tax assets of ¥89 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032. Determination of valuation allowance In accordance with ASC 740, when the MHFG Group determines whether and to what extent a valuation allowance is needed, the Group considers all available evidence, both positive and negative, to estimate future taxable income. In this regard, the Group considers reversals of existing taxable temporary differences, projected future taxable income (exclusive of reversals of existing temporary differences) and qualifying tax-planning available-for-sale tax-planning available-for-sale Positive evidence includes the Group’s results of operations for the current and preceding years on an overall consolidated basis and for most of the principal subsidiaries. In particular, the strong results of operations in recent years of MHFG’s principal banking subsidiaries in Japan represent positive evidence that can be objectively verified. Negative evidence includes the existence of significant amounts of net operating loss carryforwards or cumulative losses recorded at certain entities, and the expiration of unused net operating loss carryforwards in recent years. A valuation allowance is recorded against deferred tax assets as of the balance sheet date to the extent the Group estimates it is more likely than not that sufficient future taxable income is not available to realize such deferred tax assets. As the Group did not apply a consolidated taxation system for the fiscal year ended March 31, 2021, with a few exceptions of certain subsidiaries, deferred tax assets and liabilities are calculated separately for each legal entity. The Group has applied the consolidated taxation system from the fiscal year ended March 31, 2022 and has shifted to the Japanese Group Relief System beginning with the fiscal year ended March 31, 2023. A consolidated basis for corporate income taxes results in the reporting of taxable income or loss based upon the combined profits or losses of the parent company and its wholly-owned domestic subsidiaries. Therefore, when calculating deferred tax assets and liabilities and valuation allowance as of March 31, 2021, the Group considered the effect of the change to the consolidated taxation system. Also, when calculating deferred tax assets and liabilities and valuation allowance as of March 31, 2022, the Group considered the effect of the shift to the Japanese Group Relief System. The impact of the shift to the Japanese Group Relief System was not material to the consolidated financial statements. The changes in the valuation allowance are primarily due to changes in deductible temporary differences, net operating loss carryforwards and the estimated availability of future taxable income sources. In general, a valuation allowance is recognized against deferred tax assets related to entities that have accumulated significant net operating loss carryforwards. As of March 31, 2023, the Group’s valuation allowance was primarily related to entities in Japan, the United States and the United Kingdom. The valuation allowance was partially recognized in Japan and in the United States, while the valuation allowance was fully recognized in the United Kingdom. The Group determined whether cumulative losses were recognized by aggregating pretax results for the recent three years as part of the analysis of potential indicators of negative evidence. In each tax jurisdiction, certain entities recognized a cumulative loss on the basis of the most recent three years’ pretax results as of March 31, 2023. A valuation allowance was fully recognized against the deferred tax assets if the Group determined there was no positive evidence that overcame the negative evidence. As of March 31, 2023, MHFG’s securities subsidiary in the United Kingdom recorded cumulative losses on the basis of the recent three years’ pretax results and recognized a full valuation allowance, as there was no positive evidence to overcome the negative evidence. MHFG and its principal banking subsidiaries in Japan did not record cumulative losses in the periods presented. Change in valuation allowance The following table presents a roll-forward of the valuation allowance for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Balance at beginning of fiscal year 165,278 129,150 163,164 Changes that directly affected Income tax expense (39,410 ) 16,196 (4,118 ) Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards — — — Others 3,282 17,818 39,754 Total 3,282 17,818 39,754 Balance at end of fiscal year 129,150 163,164 198,800 The decrease in the fiscal year ended March 31, 2021 of ¥39,410 million in the valuation allowance that directly affected Income tax expense was primarily related to an increase of the realizability of deferred tax assets of MHFG and its subsidiaries. The increase in the fiscal year ended March 31, 2022 of ¥16,196 million in the valuation allowance that directly affected Income tax expense was primarily related to a decrease of the realizability of deferred tax assets of MHFG and its subsidiaries. The increase in the fiscal year ended March 31, 2022 of ¥17,818 million in others was primarily related to an increase in the valuation allowance that is fully recognized against the MHFG Group’s net operating loss carryforwards due to tax rate increase of MHFG’s foreign subsidiary. Net operating loss carryforwards At March 31, 2023, the MHFG Group had net operating loss carryforwards totaling ¥500 billion. These carryforwards are scheduled to expire as follows: Net operating loss carryforwards (1) (in billions of yen) Fiscal year ending March 31: 2024 — 2025 — 2026 156 2027 3 2028 — 2029 and thereafter (2) 341 Total 500 Notes: (1) Net operating loss carryforwards related to Japanese local taxes recorded at MHFG in the fiscal year ended March 31, 202 2 mostly (2) Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom. In addition, included in the net operating loss carryforwards in the above table are MHSC’s net operating loss carryforwards of ¥156 billion resulting mainly from the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring. The tax loss was recorded at MHSC in accordance with Japanese tax law. The net operating loss carryforwards due to this restructuring will expire during the fiscal year ending March 31, 2026. Uncertainty in income tax The following table is a roll-forward of unrecognized tax benefits for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 3,374 4,401 5,245 Gross amount of increases (decreases) related to positions taken during prior 455 (576 ) (438 ) Gross amount of increases related to positions taken during the current year 524 954 1,748 Amount of decreases related to settlements — — — Foreign exchange translation 48 466 488 Total unrecognized tax benefits at end of fiscal year 4,401 5,245 7,043 The total amount of unrecognized tax benefits including ¥1,463 million, ¥1,812 million and ¥2,286 million of interest and penalties was ¥4,401 million, ¥5,245 million and ¥7,043 million at March 31, 2021, 2022 and 2023, respectively, which would, if recognized, affect the Group’s effective tax rate. The Group classifies interest and penalties accrued relating to unrecognized tax benefits as Income tax expense. The MHFG Group is currently subject to ongoing tax audits in some jurisdictions. The oldest years open to tax audits in Japan, the United States and the United Kingdom are 2014, 2002 and 2018, respectively. The Group does not anticipate that increases or decreases of unrecognized tax benefits within the next twelve months would have a material effect on its consolidated results of operations or financial condition.

Pension and other employee bene

Pension and other employee benefit plans	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Pension and other employee benefit plans	20. Pension and other employee benefit plans Severance indemnities and pension plans MHFG and certain subsidiaries sponsor and offer their employees, other than directors and corporate auditors, contributory and non-contributory lump-sum lump-sum Certain foreign offices and subsidiaries have defined contribution plans and/or defined benefit plans, of which disclosures are combined with those for domestic benefit plans, as they are not significant and those plans don’t use significantly different assumptions. MHFG and certain subsidiaries have several defined contribution plans. The costs recognized in respect of contributions to the plans for the fiscal years ended March 31, 2021, 2022 and 2023 were ¥4,510 million, ¥3,981 million and ¥7,395 million, respectively. Pension plans are not fully integrated among subsidiaries of MHFG and plan assets are managed separately by each plan. Net periodic benefit cost and funded status The following table presents the components of net periodic benefit cost of the severance indemnities and pension plans for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Service cost-benefits earned during the fiscal year 39,672 33,190 30,460 Interest costs on projected benefit obligations 5,790 5,636 6,917 Expected return on plan assets (41,887 ) (37,051 ) (36,322 ) Amortization of prior service cost (benefits) (2,378 ) (4,820 ) (4,854 ) Amortization of net actuarial loss (gain) 1,671 (20,485 ) (19,453 ) Special termination benefits 9,569 10,791 7,269 Loss (gain) on settlement (3,945 ) — — Net periodic benefit cost 8,492 (12,739 ) (15,983 ) Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2022 2023 (in millions of yen) Net actuarial gain (loss) (36,796 ) 122,331 Amortization of net actuarial loss (gain) (20,485 ) (19,453 ) Prior service benefits (cost) (1 ) — Amortization of prior service cost (benefits) (4,820 ) (4,854 ) Total recognized in other comprehensive income (loss) before-tax (62,102 ) 98,024 Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost are as follows: 2021 2022 2023 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.38 % 0.52 % 0.82 % Rates of increase in future compensation levels 1.80 % 2.00 % 2.00 % Interest credit rates 4.38 % 4.39 % 4.45 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.37 % 0.38 % 0.52 % Rates of increase in future compensation levels 1.80-4.80 % 1.80 % 2.00 % Expected rates of return on plan assets 1.79 % 1.54 % 1.72 % Interest credit rates 4.95 % 4.38 % 4.39 % In estimating the discount rates, the MHFG Group looks to interest rates on a portfolio of high-quality fixed-income government and corporate bonds. The durations of these bonds closely match those of the benefit obligations. Discount rates are evaluated at each measurement date. The expected rate of return for each asset category is based primarily on various aspects of the long-term prospects for the economy that include historical performance and the market environment. The following table sets forth the combined funded status and amounts recognized in the accompanying consolidated balance sheets at March 31, 2022 and 2023 for the plans of MHFG and its subsidiaries: 2022 2023 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,437,843 1,377,739 Service cost 33,190 30,460 Interest cost 5,636 6,917 Plan participants’ contributions 1,089 1,053 Amendments 1 — Actuarial loss (gain) (19,939 ) (48,856 ) Foreign exchange translation 4,099 3,250 Benefits paid (54,483 ) (55,332 ) Lump-sum (29,697 ) (27,539 ) Benefit obligations at end of fiscal year 1,377,739 1,287,692 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,412,745 2,114,011 Actual return (negative return) on plan assets (8,008 ) 92,893 Foreign exchange translation 3,863 3,158 Partial withdrawal of assets from employee retirement benefits (Note) (270,172 ) (147,181 ) Employer contributions 28,977 23,613 Plan participants’ contributions 1,089 1,053 Benefits paid (54,483 ) (55,332 ) Fair value of plan assets at end of fiscal year 2,114,011 2,032,215 Funded status 736,272 744,523 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 762,147 768,998 Accrued pension liability (25,875 ) (24,475 ) Net amount recognized 736,272 744,523 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) 63,030 58,173 Net actuarial gain (loss) 421,690 524,571 Net amount recognized 484,720 582,744 Note: During the fiscal year s severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2023. No gains or losses have been recognized as a result of these transactions. The aggregated accumulated benefit obligations of these plans were ¥ million and ¥ million, as of March 31, 2022 and 2023, respectively. The defined benefit plans generally employ a multi-variable and non-linear formula based upon rank and years of service. The following table shows the projected benefit obligations and the fair value of plan assets for the plans of MHFG and its subsidiaries with projected benefit obligations in excess of plan assets, and the accumulated benefit obligations and the fair value of plan assets for the plans with accumulated benefit obligations in excess of plan assets at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 31,829 29,389 Fair value of plan assets 5,954 4,914 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 31,829 29,389 Fair value of plan assets 5,954 4,914 Note: The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets. Investment policies and asset allocation In managing plan assets, the MHFG Group determines the appropriate levels of risk that the Group can assume under the given circumstances to gain total returns from a long-term perspective while ensuring that sufficient funds will be available to plan participants and beneficiaries. The long-term asset allocation to each asset category such as Japanese equity securities, Japanese debt securities, foreign equity securities and foreign debt securities is determined based upon the optimal portfolio, which aims to gain total returns within the range of an acceptable level of risk from a long-term perspective. Additionally, the asset allocation is reviewed every five years, unless there are any significant changes in the circumstances such as market fluctuations. When selecting an investment in each asset category, the MHFG Group takes into consideration credit standing of an investee, concentration of credit risk to a certain investee and liquidity of a financial instrument among other things. The investments in each asset category are further diversified across funds, strategies and sectors along with other things. There is no significant investment in a single investee except Japanese government bonds. Certain subsidiaries of MHFG established employee retirement benefit trusts and transferred their assets to the trusts as plan assets. These assets are separated from the employer’s proprietary assets for the payment to the plan beneficiaries. The assets held in these trusts are primarily Japanese equity securities and have been entrusted directly to qualified trustees including trust banks. MHFG and certain subsidiaries’ target allocation for the plan assets, excluding those of the employee retirement benefit trusts, at March 31, 2023 is as follows: Asset category Asset ratio Japanese equity securities 3.00 % Japanese debt securities 32.00 % Foreign equity securities 26.00 % Foreign debt securities 24.00 % General account of life insurance companies 10.00 % Other 5.00 % Total 100.00 % Note: General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments. Fair value of plan assets The following table presents the fair value of plan assets of MHFG and its subsidiaries at March 31, 2022 and 2023, by asset class. For the detailed information on fair value measurements, including descriptions of Level 1, 2 and 3 of the fair value hierarchy and the valuation methodologies, see Note 26 “Fair value.” 2022 2023 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,003 — — 1,003 1,018 — — 1,018 Pooled funds (2) 13 5 — 18 5 6 — 11 Japanese debt securities: Government bonds 179 — — 179 123 — — 123 Pooled funds (2) — 10 — 10 — 8 — 8 Other — 21 — 21 — 21 — 21 Foreign equity securities: Common stocks 172 — — 172 94 — — 94 Pooled funds (2) — 7 — 7 — 8 — 8 Foreign debt securities: Government bonds 170 9 — 179 173 14 — 187 Pooled funds (2) — 10 — 10 — 3 — 3 Other — 18 — 18 — 15 — 15 General account of life insurance companies (3) — 116 — 116 — 113 — 113 Other 30 (4) (25 ) — 5 101 (4) 5 — 106 Plan assets measured at net asset value (5) 376 325 Total assets at fair value 1,567 171 — 2,114 1,514 193 — 2,032 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,003 billion and ¥1,018 billion carried at fair value at March 31, 2022 and 2023, respectively, which are well-diversified across industries. (2) These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request. (3) Investments in this class are measured at conversion value, which is equivalent to fair value. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. There were no returns on and purchases and sales of Level 3 assets during the fiscal years ended March 31, 2022 and 2023. Contributions The total contribution of approximately ¥32 billion is expected to be paid to the pension plans during the fiscal year ending March 31, 2024, based on the current funded status and expected asset return assumptions. Estimated future benefit payments The following table presents forecasted benefit payments including the effect of expected future service for the fiscal years indicated: (in millions of yen) Fiscal year ending March 31: 2024 82,311 2025 75,506 2026 75,992 2027 74,496 2028 76,348 2029-2033 330,309

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Derivative financial instruments	21. Derivative financial instruments The MHFG Group enters into derivative financial instruments in response to the diverse needs of customers, to manage the risk related to the assets and liabilities of the Group, as part of its asset and liability management, and for proprietary trading purposes. The Group is exposed primarily to market risk associated with interest rate, commodity, foreign currency, and equity products. Market risk arises from changes in market prices or indices, interest rates and foreign exchange rates that may result in an adverse change in the market value of the financial instrument or an increase in its funding costs. Exposure to market risk is managed by imposing position limits and monitoring procedures and by initiating hedging transactions. In addition to market risk, the Group is exposed to credit risk associated with counterparty default or nonperformance in respect of transactions. Counterparty credit risk arises when a counterparty fails to perform according to the terms and conditions of the contract and the value of the underlying collateral held, if applicable, is not sufficient to recover resulting losses. The exposure to counterparty credit risk is measured by the fair value of all derivatives and its potential exposure at the balance sheet dates. The exposure to counterparty credit risk is managed by entering into legally enforceable master netting agreements to mitigate the overall counterparty credit risk, requiring underlying collateral and guarantees based on an individual credit analysis of each obligor and evaluating the credit features of each instrument. In addition, credit approvals, limits and monitoring procedures are also imposed. Notional and fair value amounts of derivative instruments The following table summarizes the notional and fair value amounts of derivative instruments outstanding as of March 31, 2022 and 2023. The fair values of derivatives are presented on a gross basis; derivative receivables and payables are not offset. In addition, they are not offset against the amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under master netting agreements in the consolidated balance sheets, or the table below. Fair value Derivative receivables (2) Derivative payables (2) 2022 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,395,950 — 4,624 — 4,716 Foreign exchange contracts 217,462 — 4,436 — 4,472 Equity-related contracts 9,887 — 426 — 345 Credit-related contracts 11,857 — 118 — 121 Other contracts 681 — 119 — 116 Total 1,635,837 — 9,723 — 9,770 Fair value Derivative receivables (2) Derivative payables (2) 2023 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,991,016 — 8,374 — 8,517 Foreign exchange contracts 257,392 — 4,222 — 4,013 Equity-related contracts 7,149 — 145 — 197 Credit-related contracts 22,748 — 144 — 126 Other contracts 898 — 47 — 43 Total 2,279,203 — 12,932 — 12,896 Notes: (1) Notional amount includes the sum of gross long and gross short third-party contracts. (2) Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively. The MHFG Group provided and/or accepted cash collateral for derivative transactions under master netting agreements. The cash collateral, which was not offset against derivative positions, was included in Other assets and Other liabilities, respectively, of which the amounts were ¥1,549 billion and ¥1,076 billion at March 31, 2022, and ¥989 billion and ¥1,008 billion at March 31, 2023, respectively. Hedging activities In order to qualify for hedge accounting, a derivative must be considered highly effective at reducing the risk associated with the exposure being hedged. Each derivative must be designated as a hedge, with documentation of the risk management objective and strategy, including identification of the hedging instrument, the hedged item and the risk exposure, and how effectiveness is to be assessed prospectively and retrospectively. The extent to which a hedging instrument is effective at achieving offsetting changes in fair value or cash flows must be assessed at least quarterly. The MHFG Group’s hedging activities include net investment hedges. Net investment hedges The MHFG Group uses forward foreign exchange contracts and foreign currency-denominated debt instruments to protect the value of net investments in non-Japanese Derivative instruments not designated or qualifying as hedges The MHFG Group enters into the following derivative transactions that do not qualify for hedge accounting with a view to implementing risk management strategies: (1) interest-rate swap transactions for the purpose of economically managing the interest-rate risks in deposits, loans, etc., (2) currency swap transactions for the purpose of economically managing the foreign exchange risk of these assets, (3) equity-related derivatives for the purpose of economically managing the risk of stock price fluctuation involved in holding equity products, and (4) credit derivatives for the purpose of economically managing the credit risk in loans, residential mortgage-backed securities (“RMBS”), commercial mortgage-backed securities (“CMBS”), collateralized loan obligations (“CLO”) and other similar assets. Such derivatives are accounted for as trading positions. The changes in fair value of these instruments are primarily recorded in Trading account gains (losses)—net, even though they are used to mitigate or transform the risk of exposures arising from banking activities. The net gains (losses) resulting from changes in the fair value of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure, related to its corporate loan portfolio, is recorded in Other noninterest income (expenses). The following table summarizes gains and losses on derivatives not designated or qualifying as hedges during the fiscal years ended March 31, 2021, 2022 and 2023: Gains (losses) recorded in income 2021 2022 2023 (in millions of yen) Interest rate contracts (27,893 ) (130,312 ) (508,743 ) Foreign exchange contracts 115,181 145,979 317,459 Equity-related contracts (209,488 ) 728,226 534,615 Credit-related contracts (Note) (58,602 ) (13,877 ) (3,857 ) Other contracts 23,680 7,762 59,599 Total (157,122 ) 737,778 399,073 Note: Amounts include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively. Credit derivatives A credit derivative is a bilateral contract between a seller and a buyer of protection against the credit risk of a particular entity. Credit derivatives generally require that the seller of credit protection make payments to the buyer upon the occurrence of predefined credit events, which include bankruptcy, dissolution or insolvency of the referenced entity. The MHFG Group either purchases or writes protection on either a single name or a portfolio of reference credits. The Group enters into credit derivatives to help mitigate credit risk in its corporate loan portfolio and other cash positions, to take proprietary trading positions, and to facilitate client transactions. The notional amount of credit derivatives represents the maximum potential amount of future payments the seller could be required to make. If the predefined credit event occurs, the seller will generally have a right to collect on the underlying reference credit and the related cash flows, while being liable for the full notional amount of credit protection to the buyer. The Group manages credit risk associated with written protection by purchasing protection with identical or similar underlying reference credits, which substantially offsets its exposure. Thus, the notional amount is not necessarily a reliable indicator of the Group’s actual loss exposure. The following table summarizes the notional and fair value amounts of credit derivatives at March 31, 2022 and 2023: 2022 2023 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 3,045 38 4,497 31 Non-investment 2,122 54 5,774 62 Total 5,167 92 10,271 93 Credit protection purchased 6,690 (95 ) 12,477 (75 ) Note: The rating scale is based upon either the external ratings or the internal ratings of the underlying reference credit. The lowest investment grade rating is considered to be BBB - non-investment Non-investment The following table shows the maximum potential amount of future payments for credit protection written by expiration period at March 31, 2022 and 2023: Maximum payout/Notional amount 2022 2023 (in billions of yen) One year or less 245 331 After one year through five years 4,785 9,585 After five years 137 355 Total 5,167 10,271 Note: The maximum potential amount of future payments is the aggregate notional amount of the credit derivatives where the Group wrote the credit protection, and it has not been reduced by the effect of any amounts that the Group may possibly collect on the underlying assets and the related cash flows, nor netted against that of credit protection purchased. Credit-related contingent features Certain of the MHFG Group’s derivative instruments contain provisions that require the Group’s debt to maintain an investment grade credit rating from the major credit rating agencies. If the Group’s debt credit rating were to fall below investment grade, the counterparties to the derivative instruments could request immediate payment or demand immediate and ongoing full overnight collateralization on derivative instruments which are in net liability positions for the Group. The following table shows the quantitative information about derivative instruments with credit-risk-related contingent features at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 1,149 814 Collateral provided to counterparties in the normal course of business 1,164 663 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered — 151 Note: There was no amount that the Group would be required to post as collateral or settle immediately on March 31, 2022.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Commitments and contingencies	22. Commitments and contingencies Obligations under guarantees The MHFG Group provides guarantees or indemnifications to counterparties to enhance their credit standing and enable them to complete a variety of business transactions. A guarantee represents an obligation to make payments to third parties if the counterparty fails to fulfill its obligation under a borrowing arrangement or other contractual obligation. The types of guarantees under ASC 460, “Guarantees” (“ASC 460”) provided by the MHFG Group are described below. Performance guarantees Performance guarantees are issued to guarantee customers’ performance under contractual arrangements such as a tender bid on a construction project or the completion of a construction project. Guarantees on loans Guarantees on loans include obligations to guarantee the customers’ borrowing contracts. The MHFG Group is required to make payments to the guaranteed parties in the event that customers fail to fulfill obligations under the contracts. Guarantees on securities Guarantees on securities include obligations to guarantee securities, such as bonds issued by customers. Other guarantees Other guarantees include obligations to guarantee customers’ payments, such as tax payments. Guarantees for the repayment of trust principal The MHFG Group provides certain trust products with guarantees for the repayment of trust principal, e.g., loan trusts and certain jointly operated designated money trusts. Pursuant to Japanese trust-related laws, trustees are prohibited from compensating beneficiaries for any loss in the beneficial interests in each trust. However, under a special condition of the Japanese trust-related laws, trust banks as trustees are allowed to enter into an agreement to provide compensation for any loss in the principal of the trust. The MHFG Group manages and administers the trust assets to minimize exposures against losses from the guarantees for the repayment of trust principal, including writing-off Part of the trust account profits is set aside as a reserve in trust accounts to absorb losses in the trust asset portfolios in accordance with relevant Japanese laws concerning the trust business and/or trust agreements. Statutory reserves for loan trusts and reserves for jointly operated designated money trusts are calculated based on the trust principal or the balance of loans and other assets in the trust accounts. Since the probability of principal indemnification is considered to be remote, the MHFG Group had no related reserve for credit losses recorded in its consolidated financial statements. Liabilities of trust accounts The MHFG Group, as trustee, may enter into an agreement with a third party who is not the party to the relevant trust agreement to the extent necessary to handle the trust affairs for the purpose of fulfilling the objectives of the trust and, as such, the trustee shall be allowed to assume certain liabilities. Pursuant to Japanese trust-related laws, the trustee is ultimately liable to pay those liabilities out of its proprietary assets in the event that the trust assets are insufficient to cover those liabilities. The amount of trust liabilities rarely exceeds the amount of trust assets and, therefore, those liabilities are generally covered by the corresponding trust assets. To avoid the demand for payment out of the proprietary assets, the trustee can enter into a special covenant of limited liability under which the trust creditors agree to limit the trustee’s liability to the value of the trust assets and to waive the right for compulsory execution against the trustee’s proprietary assets. The MHFG Group regularly monitors the condition of trust accounts to minimize exposures against making payment. The amounts of such liabilities in the trust accounts, excluding those with the special covenant of limited liability, are presented in the tables below. Liabilities of trust accounts principally include obligations to return collateral under security lending transactions and other transactions. Derivative financial instruments Certain written options and credit default swaps are deemed guarantees pursuant to the definition of guarantees in ASC 460 if these contracts require the MHFG Group to make payments to counterparties based on changes in an underlying instrument or index that is related to an asset, a liability, or an equity security of the counterparties. The MHFG Group’s payments could involve a gross settlement or a net settlement. Because it is difficult in practice to determine whether the counterparty has the asset, the liability or the equity security relating to the underlying, the MHFG Group has decided to include all credit default swaps and written options, excluding written options outside the scope of ASC 460, in the guarantee disclosures. The MHFG Group records all guarantees and similar obligations subject to ASC 460 at fair value in the consolidated balance sheets at the inception of the guarantee. The total carrying amount of guarantees and similar obligation s at March 31, The table below summarizes the remaining term and maximum potential amount of future payments by type of guarantee at March 31, 2022 and 2023. The maximum potential amount of future payments disclosed below represents the contractual amounts that could be required to be repaid in the event of the guarantees being executed, without consideration of possible recoveries under recourse provisions or from collateral held. With respect to written options included in derivative financial instruments in the table below, in theory, the MHFG Group is exposed to unlimited losses; therefore, the table shows the notional amounts of the contracts as a substitute for the maximum exposure. The MHFG Group, when necessary, requires collateral such as cash, investment securities and real estate or third-party guarantees depending on the amount of credit risk involved, and employs means such as sub-participation 2022 Maximum potential/Contractual or Notional amount Amount by expiration period One year or After one year through five years After five years (in billions of yen) Performance guarantees 3,254 2,084 996 174 Guarantees on loans 419 314 42 63 Guarantees on securities 75 9 66 — Other guarantees 2,899 2,381 451 67 Guarantees for the repayment of trust principal 22 — 9 13 Liabilities of trust accounts 478 116 199 163 Derivative financial instruments 36,484 17,110 15,721 3,653 2023 Maximum potential/Contractual or Notional amount Amount by expiration period One year or After one year through five years After five years (in billions of yen) Performance guarantees 3,548 1,954 1,413 181 Guarantees on loans 228 149 26 53 Guarantees on securities 82 14 68 — Other guarantees 3,306 2,339 869 98 Guarantees for the repayment of trust principal 18 — 8 10 Liabilities of trust accounts 554 97 282 175 Derivative financial instruments 83,420 53,774 24,954 4,692 The table below presents the maximum potential amount of future payments of performance guarantees, guarantees on loans, guarantees on securities and other guarantees classified based on internal ratings at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Investment grade 5,336 5,587 Non-investment 1,311 1,577 Total 6,647 7,164 Note: Investment grade in the internal rating scale generally corresponds to BBB- Other off-balance-sheet In addition to guarantees, the MHFG Group issues other off-balance-sheet Commitments to extend credit Commitments to extend credit are legally binding agreements to lend to customers on demand. They usually have set maturity dates. These agreements differ from guarantees in that they are generally revocable or contain provisions that enable the MHFG Group to avoid payment or reduce the amount of credit extended under certain conditions, such as the deterioration of the borrower’s financial condition or other reasonable conditions. The MHFG Group monitors the financial condition of the potential borrowers throughout the commitment period to determine whether additional collateral or changes in the terms of the commitment are necessary. Since many of these commitments to extend credit expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Commitments to invest in securities Commitments to invest in securities include legally binding contracts to make additional contributions to investment funds, such as private equity funds in accordance with the terms of investment agreements. Commercial letters of credit Commercial letters of credit are issued in connection with customers’ trade transactions. Normally, the customers cannot receive the goods until they make payment to a bank, and therefore these commercial letters of credit are collateralized by the underlying goods. Upon issuance of commercial letters of credit, the MHFG Group monitors the credit risk associated with these transactions to determine if additional collateral is required. The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Commitments to extend credit (Note) 92,203 100,973 Commercial letters of credit 1,422 1,336 Total 93,625 102,309 Note: Commitments to extend credit include commitments to invest in securities. Allowance for credit losses on off-balance-sheet The amounts of allowance for credit losses on off-balance-sheet Legal proceedings and investigations The MHFG Group is involved in normal collection proceedings initiated by the Group, other legal proceedings and investigations in the ordinary course of business. In accordance with ASC 450, the Group recognizes a liability for loss contingencies arising from such proceedings and investigations when a loss is probable and the loss amount or the range of the loss can be reasonably estimated. However, if a loss is reasonably possible but the range of loss is not probable and reasonably estimable, the Group does not recognize a liability but discloses the detail of such proceedings and investigations. Based on the information available as of the date of the consolidated financial statements, the Group believes that the outcome of the collection, legal proceedings and investigations will not have a significant adverse effect on the consolidated financial statements. Leases The MHFG Group is obligated under a number of lease arrangements. The Group’s lessee arrangements mainly consist of operating leases for real estate, such as office space, including its head office, and branches. Finance leases are not significant. Some of the Group’s operating leases include variable lease payments. The following table presents the consolidated balance sheet information related to operating leases as of March 31, 2022 and 2023: 2022 2023 (in millions of yen, except for remaining lease Right-of-use (Note) 570,171 549,668 Lease liabilities (Note) 593,339 571,087 Weighted average: Remaining lease term 15.5 years 14.7 years Discount rate 0.60 % 0.66 % Note: Right-of-use The following table presents lease cost and supplemental information related to operating leases for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Lease cost (Note) 119,453 111,907 101,808 Right-of-use 108,430 51,901 65,417 Operating cash flows 102,150 101,223 86,329 Note: Lease cost for operating leases are included in Occupancy expenses on the consolidated statements of income. The Group’s variable lease costs and costs for leases with terms of twelve months or less are not significant. The following table shows future lease payments under operating leases as of March 31, 2023: As of March 31, 2023 (in millions of yen) Fiscal year ending March 31: 2024 79,207 2025 60,345 2026 53,518 2027 43,575 2028 34,048 2029 and thereafter 324,165 Total lease payments 594,858 Amount representing interest 23,771 Total lease liabilities for operating leases 571,087

Variable interest entities and

Variable interest entities and securitizations	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Variable interest entities and securitizations	23. Variable interest entities and securitizations Variable interest entities In the normal course of business, the MHFG Group is involved with VIEs primarily through the following types of transactions: asset-backed commercial paper/loan programs, asset-backed securitizations, investments in securitization products, investment funds, trust arrangements, structured finance, and funding vehicles. The Group consolidates certain of these VIEs, where the Group is deemed to be the primary beneficiary because it has both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The MHFG Group reassesses whether it is the primary beneficiary on an ongoing basis as long as the Group has any continuing involvement with the VIE. There are also other VIEs, where the Group has determined that it is not the primary beneficiary but has significant variable interests. In evaluating the significance of the variable interests, the Group takes into consideration the extent of its involvement with each VIE, such as the seniority of its investments, the share of its holding in each tranche and the variability it expects to absorb, as well as other relevant facts and circumstances. The likelihood of loss is not necessarily relevant to the determination of significance, and therefore, “significant” does not imply that there is high likelihood of loss. The maximum exposure to loss that is discussed in this section refers to the maximum loss that the Group could possibly be required to record in its consolidated statements of income as a result of its involvement with the VIEs. This represents exposures associated with both on-balance- sheet off-balance- sheet related to the VIEs. Further, this maximum potential loss is disclosed regardless of the probability of such losses and, therefore, it is not indicative of the ongoing exposure which is managed within the Group’s risk management framework. The table below shows the consolidated assets of the Group’s consolidated VIEs as well as total assets and maximum exposure to loss for its significant unconsolidated VIEs, in which the Group has determined that its maximum exposure to loss is greater than specific thresholds or meets certain other criteria as of March 31, 2022 and 2023: Consolidated VIEs Significant unconsolidated VIEs 2022 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,709 — — Asset-backed securitizations 1,363 190 90 Investments in securitization products 388 — — Investment funds 1,816 3,392 719 Trust arrangements and other 5,299 — — Total 11,575 3,582 809 Consolidated VIEs Significant unconsolidated VIEs 2023 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 3,082 — — Asset-backed securitizations 1,514 224 134 Investments in securitization products 387 — — Investment funds 2,294 3,397 845 Trust arrangements and other 4,877 — — Total 12,154 3,621 979 As of March 31, 2022 and 2023, the noncontrolling interests in consolidated VIEs amounted to ¥388 billion and ¥719 billion, respectively, and are included in the Group’s equity-classified noncontrolling interests. The Group has not provided financial or other support to consolidated or unconsolidated VIEs that the Group was not previously contractually required to provide. The tables below present the carrying amounts and classification of assets and liabilities on the MHFG Group’s balance sheets that relate to its variable interests in significant unconsolidated VIEs, as of March 31, 2022 and 2023: Assets on the MHFG Group’s balance sheets related to unconsolidated VIEs: 2022 2023 (in billions of yen) Trading account assets 143 83 Investments 430 482 Loans 92 154 Total 665 719 Liabilities on the MHFG Group’s balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2022 2023 (in billions of yen) Payables under securities lending transactions 54 — Trading account liabilities 2 1 Total 56 1 Maximum exposure to loss (Note) 809 979 Note: This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet off-balance-sheet In the table above the nature of the Group’s variable interest can take different forms, as described further in the notes below. Additionally the Group’s exposure to the obligations of VIEs is generally limited to its interest in these entities. In certain instances the Group provides undrawn commitments to the VIEs. The Group’s maximum exposure to loss presented in the table above does not include the benefit of offsetting financial instruments that are held to mitigate the risks associated with these variable interests. Furthermore, the Group’s maximum exposure to loss presented in the table above is not reduced by the amount of collateral held as part of the transaction with the VIE or any party to the VIE directly against a specific exposure to loss. Asset-backed commercial paper/loan programs The MHFG Group manages several asset-backed commercial paper/loan programs that provide its clients with off-balance-sheet Asset-backed securitizations The MHFG Group acts as an arranger of various types of structured finance schemes to meet its clients’ needs for off-balance-sheet financial asset by the client is structured to be bankruptcy remote by use of a bankruptcy remote entity, which is deemed to be a VIE because its equity holder does not have decision making rights. The MHFG Group receives fees for structuring and/or distributing the securities sold to investors. In some cases, the MHFG Group itself purchases the securities issued by the entities and/or provides loans to the VIEs. In addition, the MHFG Group establishes several single-issue and multi-issue special purpose entities that issue collateralized debt obligations (“CDO”) or CLO, synthetic CDO/CLO or other repackaged instruments to meet clients’ and investors’ financial needs. The MHFG Group also arranges securitization transactions including CMBS, RMBS and others. In these transactions, the MHFG Group acts as an underwriter, placement agent, asset manager, derivatives counterparty, and/or investor in debt and equity instruments. In these cases, the MHFG Group considers that these variable interests are not significant as the MHFG Group does not have material balance sheet or off-balance The MHFG Group manages Tender Option Bond (“TOB”) programs which are associated with trusts that hold highly-rated, fixed-rate and tax-exempt non-customer non-customer non-customer Investments in securitization products The MHFG Group invests in, among other things, various types of CDO/CLO, synthetic CDO/CLO and repackaged instruments, CMBS and RMBS arranged by third parties for the purpose of generating current income or capital appreciation, which all utilize entities that are deemed to be VIEs. By design, such investments were investment grade at issuance and held by a diverse group of investors. The potential loss amounts of the securities and the loans are generally limited to the amounts invested because the Group has no contractual involvement in such VIEs beyond its investments. Since the Group is involved in these VIEs only as an investor, the Group does not ordinarily have the power to direct the VIEs’ activities that most significantly impact the VIEs’ economic performance. Similar to the criteria noted in the asset-backed securitization section, the Group views this investment activity to be “significant” when it has a large investment share and/or provides loans to the VIEs. The Group consolidates VIEs, where the transactions are tailored by the third-party arrangers to meet the Group’s needs as a main investor, who is ultimately deemed to have the power to determine which assets are to be held by the VIEs. The Group also invests in certain beneficial interests issued by VIEs which hold real estate that the Group utilizes. In addition to these variable interests, when the Group has the power including the sole unilateral ability to liquidate the VIEs, the Group consolidates such VIEs. Investment funds The MHFG Group invests in various investment funds, including securities investment trusts, which collectively invest in equity and debt securities that include listed Japanese securities and investment grade bonds. Investment advisory companies or fund management companies, including the Group’s subsidiaries and affiliates, administer and make investment decisions about such investment funds. The Group considers that it is a “significant” variable interest when the Group’s investment share is greater than threshold. The Group consolidates certain investment funds where it is deemed to be the primary beneficiary. The Group determines whether it is the primary beneficiary by evaluating whether it has both (1) the power to make investment decisions about the investment funds and (2) the obligation to absorb losses or the right to receive benefits that could potentially be significant to the investment funds. The Group consolidates certain investment funds where it is deemed to be the primary beneficiary. Trust arrangements The MHFG Group offers a variety of asset management and administration services under trust arrangements including security investment trusts, pension trusts and trusts used in the securitization of assets originated by and transferred to third parties. The Group receives trust fees for providing services as an agent or fiduciary on behalf of beneficiaries. In these cases, the MHFG Group considers that these variable interests are not significant except for its specific involvement as noted below . With respect to guaranteed principal money trust products, the MHFG Group assumes certain risks by providing guarantees for the repayment of principal as required by the trust agreements or relevant Japanese legislation. The MHFG Group manages entrusted funds primarily through the origination of high-quality loans and other credit-related products, investing in investment grade marketable securities such as Japanese government bonds and placing cash with the MHFG Group’s subsidiary trust banks. The Group has the power to determine which assets will be held by the VIEs or to manage these assets. In addition, through the principal guarantee agreements, the Group has the obligation to absorb losses that could potentially be significant to the VIEs. Therefore, the Group consolidates such VIEs. However, the MHFG Group does not consolidate certain guaranteed principal money trusts, which invest all the entrusted funds in the MHFG Group itself, as the Group has determined that it has no variable interests. See Note 22 “Commitments and contingencies” for the balances of guaranteed trust principal that are not consolidated at March 31, 2022 and 2023. With respect to non-guaranteed non-guaranteed The MHFG Group has established a trust in August 2020, which holds the Group’s housing loans and in turn issues beneficiary interests to the Group. The Group pledges the beneficiary interests as a collateral for borrowing from the Bank of Japan. In its role as a servicer, the Group has power to direct the entity’s activities that most significantly impact the entity’s economic performance by managing mortgage loans owned by a trust. The Group considers that it is a “significant” variable interest since the Group can determine which assets will be held by the VIE. In addition, through the beneficiary interest, the Group has the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. Therefore, the Group consolidates the VIE. Special purpose entities created for structured finance The MHFG Group is involved in real estate, commercial aircraft and other vessel and machinery and equipment financing to VIEs and financing in securitized receivable. As the Group typically only provides senior financing with credit enhanced by subordinated interests and may sometimes act as an interest rate swap counterparty, the Group has determined that it does not have the power to direct the activities of the VIEs that most significantly impact the VIEs’ economic performance, or it does not have significant variable interests. Therefore, the Group does not consolidate such VIEs. Funding Vehicles The MHFG Group has established several wholly-owned off-shore Securitization The MHFG Group engages in securitization activities and securitizes mortgage loans, other loans, government and corporate securities and other types of financial assets in the normal course of business. In these securitization transactions, the Group records the transfer of a financial asset as a sale when all the accounting criteria for a sale under ASC 860 are met. These criteria are (1) the transferred financial assets are legally isolated from the Group’s creditors, (2) the transferee or beneficial interest holder has the right to pledge or exchange the transferred financial assets, and (3) the Group does not maintain effective control over the transferred financial assets. If all the criteria are not met, the transfer is accounted for as a secured borrowing. For the fiscal years ended March 31, 2021, 2022 and 2023, the MHFG Group neither made significant transfers of financial assets nor recognized significant gains or losses in securitization transactions accounted for as sales. The Group did not retain significant interests in securitization transactions accounted for as sales as of March 31, 2022 and 2023.

Noninterest income

Noninterest income	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Noninterest income	24. Noninterest income Details of Noninterest income for the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) Fee and commission income: Securities-related business (1) 170,216 184,014 190,026 Deposits-related business (1) 15,162 15,358 15,540 Lending-related business (2) (4) 158,921 162,953 193,838 Remittance business (1) 109,111 103,979 104,201 Asset management business (1) 104,753 122,014 109,358 Trust-related business (1) 122,215 141,365 130,576 Agency business (1) 31,331 36,899 36,529 Guarantee-related business (3) 31,665 35,296 41,150 Fees for other customer services (1) 169,310 178,122 163,127 Total Fee and commission income 912,684 980,000 984,345 Foreign exchange gains (losses)—net (3) 89,267 91,611 189,526 Trading account gains (losses)—net (2) 120,596 (491,947 ) (603,910 ) Investment gains (losses)—net: Debt securities (3) (22,032 ) (14,777 ) 5,167 Equity securities (3) 850,567 (60,563 ) 135,601 Equity in earnings (losses) of equity method investees—net (3) 31,027 34,587 (26,999 ) Gains on disposal of premises and equipment (3) 7,125 9,943 4,920 Other noninterest income (2) (5) 52,086 120,936 199,453 Total 2,041,320 669,790 888,103 Notes: (1) These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers” (“ASC 606”). (2) Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606. (3) These amounts are revenues from contracts that do not meet the scope of ASC 606. (4) Most of the lending-related fees such as commitment fees and arrangement fees are not within the scope of ASC 606. (5) These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 26 “Fair value” for further details. Certain Fee and commission income, Trading account gains (losses)—net and Other noninterest income outlined in the table above are considered to be revenues from contracts that are within the scope of ASC 606. The MHFG Group disaggregates Fee and commission income, which is the main part of revenues within the scope of ASC 606, by type of business or service in the table above. Fee and commission income For the MHFG Group’s accounting policy for the recognition of Fee and commission income, see Note 1 “Basis of presentation and summary of significant accounting policies.” Trust-related business fees consist of trust fees earned primarily through fiduciary asset management and administrative service and other trust-related fees, which amounted to ¥51 billion and ¥71 billion for the fiscal year ended March 31, 2021, respectively, ¥56 billion and ¥85 billion for the fiscal year ended March 31, 2022, respectively, and ¥55 billion and ¥76 billion for the fiscal year ended March 31, 2023, respectively. Trading account gains (losses)—net and Other noninterest income In addition to Fee and commission income, Trading account gains (losses)—net and Other noninterest income include certain revenues within the scope of ASC 606. Underwriting fees from trading securities, which amounted to ¥86 billion, ¥83 billion and ¥59 billion for the fiscal years ended March 31, 2021, 2022 and 2023, respectively, are within the scope of ASC 606 and accounted for in Trading account gains (losses)—net. Underwriting fees are primarily recognized on the date which all the considerations of the transaction are fixed. For the fiscal years ended March 31, 2021, 2022 and 2023, approximately ¥15 billion, ¥15 billion and ¥21 billion, respectively, of Other noninterest income were within the scope of ASC 606. Credit card interchange fees are within the scope of ASC 606 and accounted for in Other noninterest income. Credit card interchange fees are earned on credit card transactions conducted through payment networks and recognized upon settlement of the credit card payment transactions. Contract balances relating to revenues from contracts with customers subject to ASC 606 Contract assets and receivables from contracts with customers subject to ASC 606 are recognized in Accrued income or accounts receivable of Other assets. As of March 31, 2022 and 2023, the balance of contract assets was not material. Contract liabilities are recognized in unearned income of Other liabilities. As of March 31, 2022 and 2023, the balance of contract liabilities was not material. Remaining performance obligations relating to revenues from contracts with customers subject to ASC 606 Remaining performance obligations are services that the MHFG Group has committed to provide in the future in connection with its contracts with customers. As of March 31, 2022 and 2023, the amount of expected revenues from current obligations to provide services in the future was not material. It excludes revenues from contracts less than one year or contracts that have provisions that allow the Group to recognize revenue at the amount it has the right to invoice.

Trading account gains and losse

Trading account gains and losses	12 Months Ended
	Mar. 31, 2023
Trading Account Gains And Losses [Abstract]
Trading account gains and losses	25. Trading account gains and losses The MHFG Group performs trading activities through market making, sales, and arbitrage. Accordingly, Trading account gains (losses)—net include gains and losses from transactions undertaken for trading purposes, including both market making for customers and proprietary trading, or transactions through which the Group seeks to capture gains arising from short-term changes in market value. Trading account gains (losses)—net also include gains and losses related to changes in the fair value of derivatives and other financial instruments not eligible for hedge accounting under U.S. GAAP that are utilized to offset mainly interest rate risk related to the Group’s various assets and liabilities, as well as gains and losses related to changes in the fair value of foreign currency-denominated debt securities reported as Trading securities. Net trading gains (losses) for the fiscal years ended March 31, 2021, 2022 and 2023 are comprised of the following: 2021 2022 2023 (in millions of yen) Trading account gains (losses)—net: Trading securities 274,762 (1,230,330 ) (1,003,636 ) Derivative contracts: Interest rate contracts (27,893 ) (130,312 ) (508,743 ) Foreign exchange contracts (1) 115,181 145,979 317,459 Equity-related contracts (209,488 ) 728,226 534,615 Credit-related contracts (2) (55,646 ) (13,272 ) (3,204 ) Other contracts 23,680 7,762 59,599 Total 120,596 (491,947 ) (603,910 ) Foreign exchange gains (losses)—net (3) 89,267 91,611 189,526 Net trading gains (losses) 209,863 (400,336 ) (414,384 ) Notes: (1) Amounts include gains and losses on currency swaps. (2) Amounts do not include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively. The net gains (losses) is recorded in Other noninterest income (expenses). (3) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.

Fair value

Fair value	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Fair value	26. Fair value Fair value measurements ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. In addition, ASC 820 precludes (1) the deferral of gains and losses at inception of certain derivative contracts whose fair value was not evidenced by market-observable data, and (2) the use of block discounts when measuring the fair value of instruments traded in an active market, which were previously applied to large holdings of publicly traded financial instruments. Fair value hierarchy ASC 820 specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. The standard describes three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities include debt and equity securities and derivative contracts that are traded in an active exchange market. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments. If no quoted market prices are available, the fair values of debt securities and over-the-counter Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Valuation process The MHFG Group has established valuation policies which govern the principles of fair value measurements and the authority and duty of each department. The Group has also established procedure manuals which describe valuation techniques and related inputs for determining the fair values of various financial instruments. The policies require that the measurement of fair values be carried out in accordance with the procedures performed by the risk management departments or the back offices which are independent from the front offices. The policies also require the risk management departments to check and verify whether the valuation methodologies defined in the procedure manuals are fair and proper and the internal audit departments to periodically review the compliance with the procedures throughout the Group. Although the valuation methodologies and related inputs are consistently used from period to period, a change in the market environment sometimes leads to a change in the valuation methodologies and the inputs. For instance, a change in market liquidity due to a delisting or a new listing is one of the key drivers of revisions to the valuation methodologies and the inputs. The key drivers also include the availability or the lack of market observable inputs and the development of new valuation methodologies. Price verification performed through the Group’s internal valuation process has an important role in identifying whether the valuation methodologies and the inputs need to be changed. The internal valuation process over the prices broker-dealers provide, primarily for Japanese securitization products, is described in more detail below in Available-for-sale The following is a description of valuation methodologies and inputs used for assets and liabilities measured at fair value on a recurring basis, including the general classification of such instruments pursuant to the fair value hierarchy and the MHFG Group’s valuation techniques used to measure fair values. During the fiscal year ended March 31, 202 3 Trading securities and trading securities sold, not yet purchased When quoted prices for identical securities are available in an active market, the Group uses the quoted prices to measure the fair values of securities and such securities are classified in Level 1 of the fair value hierarchy. Level 1 securities include highly liquid government bonds and equity securities. When quoted prices for identical securities are available, but not actively traded, such securities are classified in Level 2 of the fair value hierarchy. When no quoted market prices are available, the Group estimates fair values by using pricing models with inputs that are observable in the market and such securities are classified in Level 2 of the fair value hierarchy. Level 2 securities include Japanese local government bonds, corporate bonds, and commercial paper. When less liquid market conditions exist for securities, the quoted prices are stale or the prices from independent sources vary significantly, such securities are generally classified in Level 3 of the fair value hierarchy. The fair values of securitization products such as RMBS, CMBS, ABS, and CLO are determined primarily by using a discounted cash flow model. The key inputs used for the model include default rates, recovery rates, prepayment rates, and discount rates. Though most securitization products are classified in Level 2, if the significant inputs are unobservable or cannot be corroborated by observable market data, these financial instruments are classified in Level 3. Hedge funds the Group invests in are primarily multi strategy funds that employ a fundamental bottom-up start-up ten-year Derivative financial instruments Exchange-traded derivatives are valued using quoted market prices and consequently are classified in Level 1 of the fair value hierarchy. However, the majority of derivatives entered into by the Group are executed over-the-counter over-the-counter over-the-counter of the instrument. The Group calculates these funding valuation adjustments incorporating the expected future funding requirements arising from the Group’s positions and the estimated market funding cost which considers the Group’s credit risk. The Group measures these valuation adjustments based on net exposure of a group of financial assets and financial liabilities to credit risk. Available-for-sale The fair values of available-for-sale non-binding Equity securities Equity securities mainly consist of marketable equity securities. The fair values of the marketable equity securities are based upon quoted market prices for identical equity securities trading as securities in an active market. Equity securities also include investments in certain investment funds measured using the NAV per share practical expedient including private equity funds and real estate funds. These securities are determined primarily using the same procedures described under Trading securities and trading securities sold, not yet purchased Other investments Other investments consist of investments held by consolidated investment companies. These companies typically hold investments in marketable and non-marketable non-marketable Non-marketable Long-term debt Fair value accounting is elected for certain long-term debt instruments with embedded derivatives. The fair values are determined using a discounted cash flow model that considers the embedded derivatives and the terms and payment structures of the notes. The fair values of the derivatives embedded in such notes are primarily derived by using the same procedures described in Derivative financial instruments Items measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis at March 31, 2022 and 2023, including those for which the MHFG Group has elected the fair value option, are summarized below: 2022 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,604 11 — 1,615 Japanese local government bonds — 145 — 145 U.S. Treasury bonds and federal agency securities 2,353 711 — 3,064 Other foreign government bonds 907 639 — 1,546 Agency mortgage-backed securities — 3,176 — 3,176 Residential mortgage-backed securities — — 8 8 Certificates of deposit and commercial paper — 640 — 640 Corporate bonds and other (2) 15 2,743 71 2,829 Equity securities 1,381 213 28 1,622 Trading securities measured at net asset value (3) 284 Derivative financial instruments: Interest rate contracts 89 4,513 22 4,624 Foreign exchange contracts — 4,404 32 4,436 Equity-related contracts 77 323 26 426 Credit-related contracts — 116 2 118 Other contracts 49 18 52 119 Available-for-sale Japanese government bonds 24,662 497 — 25,159 Japanese local government bonds — 420 — 420 U.S. Treasury bonds and federal agency securities 373 — — 373 Other foreign government bonds 363 973 — 1,336 Agency mortgage-backed securities — 451 — 451 Residential mortgage-backed securities — 40 18 58 Commercial mortgage-backed securities — 854 — 854 Japanese corporate bonds and other debt securities — 1,920 315 2,235 Foreign corporate bonds and other debt securities — 671 117 788 Equity securities: Equity securities with readily determinable fair values 3,094 61 — 3,155 Equity securities measured at net asset value (3) 210 Other investments 2 — 56 58 Total assets measured at fair value on a recurring basis 34,969 23,539 747 59,749 Liabilities: Trading securities sold, not yet purchased 3,054 2,035 — 5,089 Derivative financial instruments: Interest rate contracts 80 4,636 — 4,716 Foreign exchange contracts — 4,472 — 4,472 Equity-related contracts 122 183 40 345 Credit-related contracts — 120 1 121 Other contracts 28 36 52 116 Long-term debt (4) — 1,962 794 2,756 Total liabilities measured at fair value on a recurring basis 3,284 13,444 887 17,615 2023 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,187 7 — 1,194 Japanese local government bonds — 138 — 138 U.S. Treasury bonds and federal agency securities 1,917 1,377 — 3,294 Other foreign government bonds 658 786 — 1,444 Agency mortgage-backed securities — 5,309 — 5,309 Residential mortgage-backed securities — — — — Certificates of deposit and commercial paper — 516 — 516 Corporate bonds and other (2) — 2,406 47 2,453 Equity securities 1,859 370 21 2,250 Trading securities measured at net asset value (3) 111 Derivative financial instruments: Interest rate contracts 218 8,103 53 8,374 Foreign exchange contracts — 4,200 22 4,222 Equity-related contracts 39 73 33 145 Credit-related contracts — 143 1 144 Other contracts 15 12 20 47 Available-for-sale Japanese government bonds 15,771 678 — 16,449 Japanese local government bonds — 555 — 555 U.S. Treasury bonds and federal agency securities 376 — — 376 Other foreign government bonds 322 986 — 1,308 Agency mortgage-backed securities — 522 — 522 Residential mortgage-backed securities — 34 13 47 Commercial mortgage-backed securities — 862 — 862 Japanese corporate bonds and other debt securities — 2,008 101 2,109 Foreign corporate bonds and other debt securities — 916 90 1,006 Equity securities: Equity securities with readily determinable fair values 3,052 161 — 3,213 Equity securities measured at net asset value (3) 271 Other investments — — 63 63 Total assets measured at fair value on a recurring basis 25,414 30,162 464 56,422 Liabilities: Trading securities sold, not yet purchased 2,954 3,513 — 6,467 Derivative financial instruments: Interest rate contracts 244 8,271 2 8,517 Foreign exchange contracts — 4,005 8 4,013 Equity-related contracts 46 91 60 197 Credit-related contracts — 124 2 126 Other contracts 10 15 18 43 Long-term debt (4) — 1,844 836 2,680 Total liabilities measured at fair value on a recurring basis 3,254 17,863 926 22,043 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) The amount includes CLO and convertible bonds, which are classified in Level 3. (3) In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2022 and 2023 were ¥68 billion and ¥52 billion, respectively. (4) Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception. Items measured at fair value on a recurring basis using significant unobservable inputs (Level 3) The following table presents a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the fiscal years ended March 31, 2022 and 2023: 2022 April 1, 2021 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2022 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 9 — (2) — — — — — — (1 ) 8 — Corporate bonds and other 1,033 7 (2) — — (452 ) 143 (72 ) — (588 ) 71 3 Equity securities 29 — (2) — — — — — — (1 ) 28 1 Derivative financial instruments, net (1) Interest rate contracts 8 11 (2) — — — — — — 3 22 (22 ) Foreign exchange contracts 23 8 (2) — — — — — — 1 32 7 Equity-related contracts (21 ) (11 ) (2) — — — — — — 18 (14 ) (23 ) Credit-related contracts 2 (3 ) (2) — — — — — — 2 1 (1 ) Other contracts — 1 (2) — — — — — — (1 ) — — Available-for-sale Residential mortgage-backed securities 23 — (3) — (4) — — — — — (5 ) 18 — Commercial mortgage-backed securities 716 5 (3) (5 ) (4) — (689 ) 62 (60 ) — (29 ) — — Japanese corporate bonds and other debt securities 365 (20 ) (3) 1 (4) — (4 ) 11 — — (38 ) 315 (19 ) Foreign corporate bonds and other debt securities 132 — (3) 7 (4) — (4 ) 47 — — (65 ) 117 1 Other investments 53 2 (3) — — — 37 (3 ) — (33 ) 56 (2 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — — — — — — — Long-term debt 713 61 (5) 1 (4) 4 (6 ) — — 534 (389 ) 794 77 2023 April 1, 2022 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2023 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 8 (1 ) (2) — — — — (6 ) — (1 ) — — Corporate bonds and other 71 4 (2) — 13 (15 ) 104 (46 ) — (84 ) 47 — Equity securities 28 — (2) — — — 2 (6 ) — (3 ) 21 (1 ) Derivative financial instruments, net (1) Interest rate contracts 22 31 (2) — — — — — — (2 ) 51 (22 ) Foreign exchange contracts 32 (5 ) (2) — — — — — — (13 ) 14 (6 ) Equity-related contracts (14 ) (26 ) (2) — — — — — — 13 (27 ) (107 ) Credit-related contracts 1 (1 ) (2) — — — — — — (1 ) (1 ) (5 ) Other contracts — 2 (2) — — — — — — — 2 2 Available-for-sale Residential mortgage-backed securities 18 — (3) — (4) — — — — — (5 ) 13 — Commercial mortgage-backed securities — — (3) — (4) — — — — — — — — Japanese corporate bonds and other debt securities 315 — (3) 3 (4) — — 25 — — (242 ) 101 8 Foreign corporate bonds and other debt securities 117 — (3) 1 (4) — (54 ) 63 — — (37 ) 90 — Other investments 56 3 (3) — — (1 ) 36 — — (31 ) 63 1 Liabilities: Trading securities sold, not yet purchased — — (2) — — — (1 ) 1 — — — — Long-term debt 794 29 (5) 10 (4) 1 (2 ) — — 323 (241 ) 836 60 Notes: (1) Total Level 3 derivative exposures have been netted on the table for presentation purposes only. (2) Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses). (3) Gains (losses) in Earnings are reported in Investment gains (losses)—net. (4) Gains (losses) in OCI are reported in Other comprehensive income (loss). (5) Gains (losses) in Earnings are reported in Other noninterest income (expenses). (6) Amounts represent total gains or losses recognized in earnings and other comprehensive income (loss) during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2022 and 2023. The amounts of unrealized gains (losses) in other comprehensive income (loss) are related to Available-for-sale securities and Long-term debt, which were ¥2 billion and ¥2 billion, respectively, at March 31, 2022, and ¥8 billion and ¥11 billion, respectively, at March 31, 2023. Transfers between levels During the fiscal year ended March 31, 2022, the transfers out of Level 3 included ¥452 billion of Trading securities and ¥693 billion of Available-for-sale Available-for-sale primarily due to assessing the significance of unobservable inputs for certain corporate bonds and other debt securities. The Group changed the criteria for the quantitative sensitivity analysis for these securities to assess the significance of unobservable inputs, such as prepayment rate, default rate, and recovery rate. Transfers out of Level 3 for Available-for-sale Other than the above transfers between levels, during the fiscal year ended March 31, 2022, the transfers out of Level 3 included ¥4 billion of Available-for-sale Available-for-sale During the fiscal year ended March 31, 2023, the transfers into Level 3 included ¥13 billion of Trading securities and ¥ 1 billion of Long-term debt. Transfers into Level 3 for Trading securities were primarily due to decreased price transparency billion of Trading securities, ¥54 billion of Available-for-sale securities, ¥2 billion of Long-term debt and ¥1 billion of Other investments. Transfers out of Level 3 for Trading securities were primarily due to increased price transparency for certain foreign bonds. Transfers out of Level 3 for Available-for-sale securities were primarily due to increased price transparency price transparency Quantitative information about Level 3 fair value measurements The following table presents information about significant unobservable material liabilities at March 31, 2022 and 2023: 2022 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (4) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale securities: Residential mortgage-backed securities 26 Discounted cash flow Prepayment rate 0.4%–18.1% 5.8% Price-based Default rate 0.0%–0.5% 0.0% Recovery rate 100.0%–100.0% 100.0% Discount margin 30.0bps–167.1bps 53.1bps Corporate bonds and other debt securities 503 Discounted cash flow Prepayment rate (1) 5.8%–24.5% 24.3% Price-based Default rate (1) 0.2%–59.7% 0.7% Recovery rate (1) 10.0%–39.7% 39.5% Discount margin (1) 35.4bps–102.5bps 47.1bps Discount margin (2) 3.9bps–446.6bps 340.4bps Derivative financial instruments, net: Interest rate contracts 22 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% Foreign exchange contracts 32 Internal valuation model (3) FX – IR correlation 11.4%–52.3% 31.4% FX – FX correlation 41.4%–64.8% 53.1% Equity-related contracts (14 ) Internal valuation model (3) Equity – IR correlation 25.0%–25.0% 25.0% Equity correlation 3.2%–100.0% 89.9% Equity volatility 12.6%–120.5% 47.3% Credit-related contracts 1 Internal valuation model (3) Default rate 0.1%–8.0% 1.5% Credit correlation 42.6%–100.0% 66.2% Other contracts — Internal valuation model (3) Commodity volatility 0.0%–89.4% 55.4% Long-term debt 794 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% FX – IR correlation 11.4%–52.3% 38.9% FX – FX correlation 41.4%–64.8% 53.1% Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation -16.9%–16.8% 0.0% Equity correlation 3.2%–100.0% 89.6% Equity volatility 8.7%–120.5% 34.0% Default rate 0.1%–8.0% 1.5% Credit correlation 18.6%–100.0% 63.9% 2023 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (4) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 13 Discounted cash flow Prepayment rate 0.2%–17.6% 4.4% Price-based Default rate 0.0%–2.2% 0.2% Recovery rate 100.0%–100.0% 100.0% Discount margin 30.0bps–167.1bps 47.0bps Corporate bonds and other debt 238 Discounted cash flow Prepayment rate (1) 21.7%–21.7% 21.7% Price-based Default rate (1) 0.2%–0.2% 0.2% Recovery rate (1) 40.5%–40.5% 40.5% Discount margin (1) 98.8bps–209.9bps 116.2bps Discount margin (2) 3.5bps–171.2bps 20.1bps Derivative financial instruments, net: Interest rate contracts 51 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% Foreign exchange contracts 14 Internal valuation model (3) FX – IR correlation 5.5%–58.2% 39.9% FX – FX correlation 39.0%–64.7% 51.9% Equity-related contracts (27 ) Internal valuation model (3) Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation 0.0%–60.0% 33.7% Equity correlation 73.9%–100.0% 96.7% Equity volatility 10.3%–95.4% 44.1% Credit-related contracts (1 ) Internal valuation model (3) Default rate 0.1%–12.2% 2.1% Other contracts 2 Internal valuation model (3) Commodity volatility 20.0%–54.5% 39.8% Long-term debt 836 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% FX – IR correlation 5.5%–58.2% 39.9% FX – FX correlation 39.0%–64.7% 51.9% Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation -16.3%–93.3% 0.0% Equity correlation 3.2%–100.0% 90.8% Equity volatility 5.9%–180.8% 34.1% Default rate 0.1%–13.1% 2.3% Credit correlation 47.6%–100.0% 68.3% Notes: (1) These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS. (2) This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds. (3) Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model. (4) Averages are calculated by weighting each input by the relative fair value of the respective financial instruments except for derivative related inputs where medians are used. (5) The range of inputs for equity securities is not disclosed, as there is a dispersion of values given the number of positions. IR = Interest rate FX = Foreign exchange Uncertainty of fair value measurements relating to unobservable inputs and interrelationships among unobservable inputs The following is a description of the uncertainty of the fair value measurements from the use of significant unobservable inputs and a description of interrelationships of the significant unobservable inputs used to measure the fair values of Level 3 assets and liabilities. (1) Prepayment rate The prepayment rate is the estimated rate at which voluntary unscheduled repayments of the principal of the underlying assets are expected to occur. The movement of the prepayment rate is generally negatively correlated with borrower delinquency. A change in prepayment rate would impact the valuation of the fair values of financial instruments either positively or negatively, depending on the structure of financial instruments. (2) Default rate The default rate is an estimate of the likelihood of not collecting contractual payments. An increase in the default rate would generally be accompanied by a decrease in the recovery rate and an increase in the discount margin. It would also generally impact the valuation of the fair values of financial instruments negatively. (3) Recovery rate The recovery rate is an estimate of the percentage of contractual payments that would be collected in the event of a default. An increase in recovery rate would generally be accompanied by a decrease in the default rate. It would also generally impact the valuation of the fair values of financial instruments positively. (4) Discount margin The discount margin is the portion of the interest rate over a benchmark market interest rate such as Tokyo Interbank Offered Rate (“TIBOR”) or swap rates. It primarily consists of a risk premium component which is the amount of compensation that market participants require due to the uncertainty inherent in the financial instruments’ cash flows resulting from credit risk. An increase in discount margin would generally impact the valuation of the fair values of financial instruments negatively. (5) Correlation Correlation is the likelihood of the movement of one input relative to another based on an established relationship. The change in correlation would impact the valuation of derivatives either positively or negatively, depending on the nature of the underlying assets. (6) Volatility Volatility is a measure of the expected change in variables over a fixed period of time. Some financial instruments benefit from an increase in volatility and others benefit from a decrease in volatility. Generally, for a long position in an option, an increase in volatility would result in an increase in the fair values of financial instruments. Items measured at fair value on a nonrecurring basis Certain assets and liabilities are measured at fair value on a nonrecurring basis. These assets and liabilities primarily include items that are measured at the lower of cost or fair value, and items that were initially measured at cost and have been written down to fair value as a result of impairment. The following table shows the fair value hierarchy for these items as of March 31, 2022 and 2023: 2022 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 81 — — 81 128 Loans held-for-sale 76 — 27 49 77 Equity securities (without readily determinable fair values) 4 — 3 1 4 Premises and equipment—net — — — — 13 Other assets — — — — 3 Total assets measured at fair value on a nonrecurring basis 161 — 30 131 225 2023 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 97 — — 97 165 Loans held-for-sale 216 — 16 200 282 Equity securities (without readily determinable fair values) 4 — 4 — 5 Other investments 94 93 — 1 122 Premises and equipment—net 1 — — 1 2 Total assets measured at fair value on a nonrecurring basis 412 93 20 299 576 Note: The fair values may not be current as of the dates indicated, but rather as of the date the fair value change occurred. Accordingly, the carrying values may not equal current fair value. Loans in the table above became nonaccrual and are measured based upon the observable market price of the loan, which is classified as Level 2, or the fair value of the underlying collateral, which is classified as Level 3. Loans held-for-sale Loans held-for-sale classified as Level 3 were measured at fair value based on market comparables. The significant unobservable inputs were price, whose ranges were from ¥97.0 to ¥100.0 and from ¥0.0 to ¥99.6 at March 31, 2022 and 2023, respectively. The weighted averages were ¥99.0 and ¥77.6 at March 31, 2022 and 2023, respectively. Equity securities (without readily determinable fair values) in the table above consist of non-marketable non-marketable non-marketable judgment or estimation is required in the determination of the fair values of non-marketable non-marketable Other investments in the table above include certain equity method investments which have been impaired and written down to fair value. The fair values of the impaired marketable equity method investments are determined by their quoted market prices. As the securities are traded on an active exchange market, they are classified as Level 1. The fair values of the impaired non-marketable equity method investments are determined primarily by using a liquidation value technique. As significant management judgment or estimation is required in the determination of the fair values of non-marketable equity method investments, they are classified as Level 3. There were no other investments measured at fair value on a nonrecurring basis as of March 31, 2022. Premises and equipment—net and Other assets in the table above have been impaired and written down to fair value. There were no other assets measured at fair value on a nonrecurring basis as of March 31, 2023. Fair value option The MHFG Group elected the fair value option for certain eligible financial instruments described below. Foreign currency denominated debt securities The MHFG Group elected the fair value option for foreign currency denominated debt securities to mitigate the volatility in earnings due to the difference in the recognition of foreign exchange risk between foreign currency denominated debt securities and financial liabilities. Following the election of the fair value option, these debt securities are reported as trading securities in Trading account assets. Certain hybrid financial instruments The MHFG Group issues structured notes as part of its client-driven activities. Structured notes are debt instruments that contain embedded derivatives. The Group elected the fair value option for certain structured notes to mitigate accounting mismatches and to achieve operational simplifications. Fair value option has only been elected for part of the portfolio as the Group would not achieve operational simplifications. In addition, the Group measures certain notes that contain embedded derivatives at fair value under the practicability exception. These notes continue to be reported in Long-term debt and interest on these notes continues to be reported in Interest expense on long-term debt based on the contractual rates. Only an immaterial amount included in Long-term debt in the statement of financial position is not eligible for fair value option. The differences between the aggregate fair value of these notes and the aggregate unpaid principal balance of such instruments were ¥90 billion and ¥161 billion at March 31, 2022 and 2023, respectively. The net unrealized gains (losses) resulting from changes in fair values of these notes recorded in Other noninterest income (expenses) were of ¥(10) billion, ¥38 billion and ¥54 billion for the fiscal years ended March 31, 2021, 2022 and 2023, respectively. Changes in fair value resulting from changes in instrument-specific credit risk were estimated by incorporating the Company’s current credit spreads observable in the bond market. Fair value of financial instruments ASC 825, “Financial Instruments” (“ASC 825”), requires the disclosure of the estimated fair value of financial instruments. The fair value of financial instruments is the amount that would be exchanged between willing parties, other than in a forced sale or liquidation. Quoted market prices, if available, are best utilized as estimates of the fair values of financial instruments. However, since no quoted market prices are available for certain financial instruments, fair values for such financial instruments have been estimated based on management’s assumptions, discounted cash flow models or other valuation techniques. Such estimation methods are described in more detail below. These estimates could be significantly affected by different sets of assumptions. There are certain limitations to management’s best judgment in estimating fair values of financial instruments and inherent subjectivity involved in estimation methodologies and assumptions used to estimate fair value. Accordingly, the net realizable or liquidation values could be materially different from the estimates presented below. The following is a description of the valuation methodologies used for estimating the fair value of financial assets and liabilities not carried at fair value on the MHFG Group’s consolidated balance sheets. Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions The carrying value of short-term financial assets, such as cash and due from banks, interest-bearing deposits in other banks, call loans

Offsetting of financial assets

Offsetting of financial assets and financial liabilities	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Offsetting of financial assets and financial liabilities	27. Offsetting of financial assets and financial liabilities Derivatives The MHFG Group enters into master netting arrangements such as International Swaps and Derivatives Association, Inc. (“ISDA”) or similar agreements with counterparties to manage mainly credit risks associated with counterparty default. If the predetermined events including counterparty default occur, these enforceable master netting arrangements or similar agreements give the Group the right to offset derivative receivables and derivative payables and related financial collateral such as cash and securities with the same counterparty. Repurchase and resale agreements and securities lending and borrowing transactions Repurchase and resale agreements and securities lending and borrowing transactions are generally covered by industry standard master repurchase agreements and industry standard master securities lending agreements with netting terms to manage mainly credit risks associated with counterparty default. In the event of default by the counterparty, these agreements with netting terms provide the Group with the right to offset receivables and payables related to such transactions with the same counterparty, and to liquidate the collateral held. The following table provides information about the offsetting of financial assets and financial liabilities at March 31, 2022 and 2023. The table includes derivatives, repurchase and resale agreements, and securities lending and borrowing transactions that are subject to enforceable master netting arrangements or similar agreements irrespective of whether or not they are offset on the Group’s consolidated balance sheets. Amounts not offset on the balance sheet (3) Gross amounts recognized Gross amounts offset on the balance sheet Net amounts presented on the balance sheet (2) Financial instruments (4) Cash collateral Net amounts (in billions of yen) 2022 Assets (1) Derivatives 9,723 — 9,723 (5) (7,232 ) (891 ) 1,600 Receivables under resale agreements 12,751 — 12,751 (6) (11,437 ) — 1,314 Receivables under securities borrowing transactions 2,339 — 2,339 (7) (2,299 ) — 40 Total 24,813 — 24,813 (20,968 ) (891 ) 2,954 Liabilities (1) Derivatives 9,770 — 9,770 (5) (6,716 ) (1,329 ) 1,725 Payables under repurchase agreements 20,070 — 20,070 (6) (19,366 ) — 704 Payables under securities lending transactions 1,361 — 1,361 (7) (1,164 ) — 197 Total 31,201 — 31,201 (27,246 ) (1,329 ) 2,626 2023 Assets (1) Derivatives 12,932 — 12,932 (5) (10,476 ) (821 ) 1,635 Receivables under resale agreements 11,695 — 11,695 (6) (10,565 ) — 1,130 Receivables under securities borrowing transactions 1,892 — 1,892 (7) (1,866 ) — 26 Total 26,519 — 26,519 (22,907 ) (821 ) 2,791 Liabilities (1) Derivatives 12,896 — 12,896 (5) (10,141 ) (843 ) 1,912 Payables under repurchase agreements 25,737 — 25,737 (6) (25,113 ) — 624 Payables under securities lending transactions 886 — 886 (7) (755 ) — 131 Total 39,519 — 39,519 (36,009 ) (843 ) 2,667 Notes: (1) Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off over-the-counter OTC-cleared (2) Derivative assets and liabilities are recorded in Trading account assets and Trading account liabilities, respectively. (3) Amounts do not exceed the net amounts presented on the balance sheet and do not include the effect of overcollateralization, where it exists. (4) For derivatives, amounts include derivative assets or liabilities and securities collateral that are eligible for offsetting under enforceable master netting arrangements or similar agreements. (5) The amounts of derivative assets and liabilities subject to enforceable master netting arrangements or similar agreements were ¥9,326 billion and ¥9,235 billion, respectively, at March 31, 2022, and ¥12,574 billion and ¥12,432 billion, respectively, at March 31, 2023. (6) The amounts of Receivables under resale agreements and Payables under repurchase agreements subject to enforceable industry standard master repurchase agreements with netting terms were ¥11,537 billion and ¥19,505 billion, respectively, at March 31, 2022, and ¥10,587 billion and ¥25,147 billion , (7) The amounts of Receivables under securities borrowing transactions and Payables under securities lending transactions subject to enforceable industry standard master lending agreements with netting terms were ¥2,339 billion and ¥1,172 billion, respectively, at March 31, 2022, and ¥1,892 billion and ¥758 billion ,

Repurchase agreements and secur

Repurchase agreements and securities lending transactions accounted for as secured borrowings	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Repurchase agreements and securities lending transactions accounted for as secured borrowings	28. Repurchase agreements and securities lending transactions accounted for as secured borrowings The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by remaining contractual maturity at March 31, 2022 and 2023: Overnight and continuous Up to 30 days 31-90 days Greater than 90 days Total (in billions of yen) 2022 Repurchase agreements 7,011 10,621 1,340 1,098 20,070 Securities lending transactions 1,098 74 — 189 1,361 Total 8,109 10,695 1,340 1,287 21,431 2023 Repurchase agreements 2,285 16,508 5,471 1,473 25,737 Securities lending transactions 685 73 — 128 886 Total 2,970 16,581 5,471 1,601 26,623 The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by class of underlying collateral at March 31, 2022 and 2023: Repurchase agreements Securities lending transactions (in billions of yen) 2022 Japanese government bonds and Japanese local government bonds 1,714 217 Foreign government bonds and foreign agency mortgage-backed securities 17,445 90 Commercial paper and corporate bonds 271 52 Equity securities 609 989 Other 31 13 Total 20,070 1,361 2023 Japanese government bonds and Japanese local government bonds 6,114 102 Foreign government bonds and foreign agency mortgage-backed securities 17,475 73 Commercial paper and corporate bonds 430 — Equity securities 1,491 711 Other 227 — Total 25,737 886 The MHFG Group is required to post securities as collateral with a fair value equal to or in excess of the principal amount of the cash borrowed under repurchase agreements. For securities lending transactions, the Group receives collateral in the form of cash. These contracts involve risks, including (1) the counterparty may fail to return the securities at maturity and (2) the fair value of the securities posted may decline below the amount of the Group’s obligation and therefore the counterparty may require additional amounts. The Group attempts to mitigate these risks by entering into transactions mainly with central counterparty clearing houses which revalue assets and perform margin maintenance activities on a regular basis, diversifying the maturities and counterparties, and using mainly highly liquid securities.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Related Party Transactions	29. Related party transactions The banking subsidiaries of MHFG make loans to the MHFG Group’s directors, executive officers, and other related parties. At March 31, 2022 and 2023, the aggregate loans to the Group’s equity method investees amounted to ¥604 billion and ¥732 billion, respectively, and outstanding loans to MHFG Group’s directors, executive officers, and other related parties were not considered significant. There were no loans to related parties that were considered nonaccrual. During the fiscal years ended March 31, 2022 and 2023, certain subsidiaries of MHFG partially withdrew assets from employee retirement benefit trusts, which were established for the payment of employees’ severance pay and retirement pensions. See Note 20 “Pension and other employee benefit plans” for further details. In addition, the other transactions with the related parties excluding loan transactions and partial withdrawal of assets from employee retirement benefit trusts, are considered immaterial. Summarized Financial Information of the MHFG Group’s Equity Method Investees Summarized financial information of the MHFG Group’s equity method investees as of March 31, 2022 and 2023, and for each of the three years ended March 31, 2023, is as follows: 2022 2023 (in billions of yen) Loans 7,765 6,037 Total assets 30,180 29,367 Deposits 8,713 6,216 Total liabilities 27,474 26,506 Total equity 2,706 2,861 Noncontrolling interests 14 16 2021 2022 2023 (in billions of yen) Total interest and dividend income 570 625 750 Total interest expense 188 182 239 Provision (credit) for credit losses 91 104 96 Net interest income after provision (credit) for credit losses 291 339 415 Income before income tax expense 237 332 261 Net income 178 246 194

Business segment information

Business segment information	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Business segment information	30. Business segment information The MHFG Group consists of the following five in-house The services that each in-house Retail & Business Banking Company This company provides financial services for individual customers, small and medium-sized Corporate & Institutional Company This company provides financial services for large corporations, financial institutions and public corporations in Japan. Global Corporate Company This company provides financial services for Japanese overseas affiliated corporate customers and non-Japanese Global Markets Company This company invests in financial products with market risk, such as interest rate risk, equity risk, and credit risk. Asset Management Company This company develops financial products and provides financial services that match the asset management needs of its wide range of customers from individuals to institutional investors. The reportable segment information, set forth below, is derived from the internal management reporting systems used by management to measure the performance of the Group’s operating segments. Management measures the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. In addition, the format and information are presented primarily on the basis of Japanese GAAP. Therefore, they are not consistent with the consolidated financial statements prepared in accordance with U.S. GAAP. A reconciliation is provided for the total amount of all business segments’ “Net business profits (losses) + Net gains (losses) related to ETFs and others” with income before income tax expense under U.S. GAAP, and the total amount of all business segments’ “Fixed assets” with the total amount of Premises and equipment-net, right-of-use The MHFG Group partially restructured in-house segments. MHFG (Consolidated) 2021 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 699.4 475.5 519.0 495.9 50.8 (39.8 ) 2,200.8 General and administrative expenses (3) 642.5 209.8 292.4 224.3 33.0 6.7 1,408.7 Equity in earnings (losses) of equity method investees—net 5.4 3.9 13.2 — 1.2 (3.8 ) 19.9 Amortization of goodwill and others 2.3 0.1 0.4 0.8 7.6 1.0 12.2 Net business profits (losses) (4) 60.0 269.5 239.4 270.8 11.4 (51.3 ) 799.8 Fixed assets (5) 532.8 192.5 169.5 98.1 — 762.8 1,755.7 MHFG (Consolidated) 2022 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 715.0 494.4 592.8 388.1 59.5 4.7 2,254.5 General and administrative expenses (3) 623.7 201.4 300.0 234.7 33.4 21.8 1,415.0 Equity in earnings (losses) of equity method investees—net 5.9 3.8 16.0 — 1.5 (1.8 ) 25.4 Amortization of goodwill and others 2.2 0.1 0.4 0.8 7.2 1.0 11.7 Net business profits (losses) (4) 95.0 296.7 308.4 152.6 20.4 (19.9 ) 853.2 Fixed assets (5) 493.0 159.1 161.8 88.5 — 794.9 1,697.3 MHFG (Consolidated) 2023 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 704.0 502.3 672.2 321.2 55.2 25.3 2,280.2 General and administrative expenses (3) 611.6 197.3 323.0 258.0 35.2 48.5 1,473.6 Equity in earnings (losses) of equity method investees—net (17.0 ) 6.4 22.8 — 0.2 (0.5 ) 11.9 Amortization of goodwill and others 2.1 0.1 0.7 0.8 6.8 0.9 11.4 Net business profits (losses) (4) 73.3 311.3 371.3 62.4 13.4 (24.6 ) 807.1 Fixed assets (5) 489.3 150.1 173.7 87.9 — 777.6 1,678.6 Notes: (1) Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates. (2) “Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated (3) “General and administrative expenses” excludes non-allocated (4) Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses (excluding non-allocated amortization of goodwill and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan. (5) “Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net; right-of-use (6) “Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including elimination of internal transaction between each segment; • equity in earnings (losses) of equity method investees—net that are not subject to allocation; and • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value. Reconciliation As explained above, the measurement bases of the internal management reporting systems and the income and expenses items included are different from the accompanying consolidated statements of income. Therefore, it is impracticable to present reconciliations of all the business segment’s information, other than net business profits (losses), to the corresponding items in the accompanying consolidated statements of income. A reconciliation of “Net business profits (losses) + Net gains (losses) related to ETFs and others” for the fiscal years ended March 31, 2021, 2022 and 2023 presented above to income (loss) before income tax expense (benefit) shown on the consolidated statements of income and a reconciliation of “Fixed assets” at March 31, 2022 and 2023 to the total amount of Premises and equipment-net, right-of-use 2021 2022 2023 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 799.8 853.2 807.1 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated 6.3 33.7 39.7 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (209.9 ) (255.9 ) (96.7 ) Gains on reversal of reserves for possible losses on loans, and others 4.9 20.8 7.4 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others 10.1 (45.8 ) 84.6 Net extraordinary gains (losses) 115.9 44.0 (10.6 ) Others (74.9 ) (46.1 ) (52.5 ) Income before income tax expense under Japanese GAAP 652.2 603.9 779.0 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (86.4 ) (124.0 ) (373.2 ) Investments 523.5 (600.1 ) (210.5 ) Loans (16.9 ) (18.3 ) (30.3 ) Allowances for credit losses 83.3 51.5 (9.8 ) Premises and equipment (56.5 ) (68.5 ) (29.3 ) Land revaluation 6.4 6.4 5.6 Business combinations (1.0 ) 6.9 8.9 Pension liabilities (153.2 ) (94.4 ) (71.6 ) Consolidation of variable interest entities 104.6 42.3 0.8 Foreign currency translation (31.5 ) (51.0 ) (5.2 ) Others 4.3 2.8 4.8 Income (loss) before income tax expense (benefit) under U.S. GAAP 1,028.8 (242.5 ) 69.2 2021 2022 2023 (in billions of yen) Fixed assets 1,755.7 1,697.3 1,678.6 U.S. GAAP adjustments (Note) 816.1 717.6 662.6 Premises and equipment-net, right-of-use 2,571.8 2,414.9 2,341.2 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from right-of-use

Foreign activities

Foreign activities	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Foreign activities	31. Foreign activities The following table presents consolidated income statement and total assets information by major geographic area. Foreign activities are defined as business transactions that involve customers residing outside of Japan. However, as the MHFG Group’s operations are highly integrated globally, estimates and assumptions have been made for an allocation among the geographic areas. Americas Japan United States of America Others Europe Asia/Oceania excluding Japan, and others Total (in billions of yen) Fiscal year ended March 31, 2021: Total revenue (1) 2,290.8 503.8 154.5 188.7 360.1 3,497.9 Total expenses (2) 1,918.2 243.5 14.4 115.8 177.2 2,469.1 Income before income tax expense 372.6 260.3 140.1 72.9 182.9 1,028.8 Net income 235.6 227.4 137.2 60.9 156.9 818.0 Total assets at end of fiscal year 152,613.7 31,939.9 4,405.3 14,150.6 18,542.0 221,651.5 Fiscal year ended March 31, 2022: Total revenue (1) 991.1 562.9 41.7 184.8 333.2 2,113.7 Total expenses (2) 1,713.8 265.0 19.0 189.2 169.2 2,356.2 Income (loss) before income tax expense (benefit) (722.7 ) 297.9 22.7 (4.4 ) 164.0 (242.5 ) Net income (loss) (509.0 ) 275.2 18.3 (16.3 ) 130.3 (101.5 ) Total assets at end of fiscal year 155,111.2 36,765.7 3,667.9 15,795.9 20,210.0 231,550.7 Fiscal year ended March 31, 2023: Total revenue (1) 1,104.7 1,841.5 93.1 445.9 791.7 4,276.9 Total expenses (2) 1,784.1 1,455.4 84.7 413.0 470.5 4,207.7 Income (loss) before income tax expense (benefit) (679.4 ) 386.1 8.4 32.9 321.2 69.2 Net income (loss) (554.7 ) 297.2 1.8 19.9 269.8 34.0 Total assets at end of fiscal year 161,348.7 45,516.4 3,579.6 16,634.7 21,701.3 248,780.7 Notes: (1) Total revenue is comprised of Interest and dividend income and Noninterest income. (2) Total expenses are comprised of Interest expense, Provision (credit) for credit losses and Noninterest expenses.

Mizuho Financial Group, Inc., p

Mizuho Financial Group, Inc., parent company	12 Months Ended
	Mar. 31, 2023
Condensed Financial Information Disclosure [Abstract]
Mizuho Financial Group, Inc., parent company	32. Mizuho Financial Group, Inc., parent company The following tables present the parent company only financial information of MHFG: Condensed balance sheets 2022 2023 (in millions of yen) Assets: Cash and due from banking subsidiaries 51,356 47,425 Interest-bearing deposits in banking subsidiaries 414 450 Investments in subsidiaries and affiliated companies: Banking subsidiaries 8,102,149 7,996,767 Non-banking 878,776 1,075,322 Long-term loans receivable from subsidiaries: A banking subsidiary 7,942,367 8,768,725 A non-banking 399,000 444,000 Other assets 648,946 545,744 Total 18,023,008 18,878,433 Liabilities and shareholders’ equity: Short-term borrowings from a banking subsidiary 755,000 810,000 Long-term debt 7,957,710 8,741,729 Other liabilities 396,086 411,213 Shareholders’ equity 8,914,212 8,915,491 Total 18,023,008 18,878,433 Condensed statements of income 2021 2022 2023 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 214,473 197,717 209,257 Non-banking 17,499 82,105 62,698 Management fees from subsidiaries 36,334 40,462 43,900 Interest income on loans and discounts 128,697 133,215 177,137 Gains on sales of investments in subsidiaries 40 53,005 — Other income 11,970 11,319 37,319 Total 409,013 517,823 530,311 Expenses: Operating expenses 37,979 43,192 52,887 Interest expense 130,812 130,453 175,723 Losses on sales of investments in a subsidiary — 26,606 — Other expense 8,842 5,946 2,768 Total 177,633 206,197 231,378 Equity in undistributed net income (loss) of subsidiaries and affiliated companies—net 341,369 (505,891 ) (307,879 ) Income (loss) before income tax expense (benefit) 572,749 (194,265 ) (8,946 ) Income tax expense (benefit) (9,016 ) (89,543 ) 5,063 Net income (loss) 581,765 (104,722 ) (14,009 ) Condensed statements of cash flows 2021 2022 2023 (in millions of yen) Cash flows from operating activities: Net income (loss) 581,765 (104,722 ) (14,009 ) Adjustments and other (390,748 ) 351,484 394,191 Net cash provided by operating activities 191,017 246,762 380,182 Cash flows from investing activities: Net change in loans (1,167,385 ) (72,313 ) (511,934 ) Purchases of premises and equipment (41,382 ) (26 ) (81 ) Proceeds from sales of premises and equipment 55,624 11 — Purchases of investments in a subsidiary — — (179,210 ) Proceeds from sales of investments in subsidiaries 125 452,500 721 Net change in other investing activities (1,370 ) 223 (5,591 ) Net cash provided by (used in) investing activities (1,154,388 ) 380,395 (696,095 ) Cash flows from financing activities: Net change in short-term borrowings (10,000 ) (95,000 ) 55,000 Proceeds from issuance of long-term debt 1,477,385 930,033 1,497,032 Repayment of long-term debt (310,000 ) (1,256,720 ) (1,030,099 ) Purchases of treasury stock (1,849 ) (1,927 ) (1,575 ) Dividends paid (190,498 ) (196,783 ) (209,457 ) Net change in other financing activities 65 44 1,117 Net cash provided by (used in) financing activities 965,103 (620,353 ) 312,018 Net increase (decrease) in cash and cash equivalents 1,732 6,804 (3,895 ) Cash and cash equivalents at beginning of fiscal year 43,234 44,966 51,770 Cash and cash equivalents at end of fiscal year 44,966 51,770 47,875

Basis of presentation and sum_2

Basis of presentation and summary of significant accounting policies (Policies)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Basis of presentation	Basis of presentation Mizuho Financial Group, Inc. (“MHFG”) is a joint stock corporation with limited liability under the laws of Japan. MHFG is a holding company for Mizuho Bank, Ltd. (“MHBK”), Mizuho Trust & Banking Co., Ltd. (“MHTB”), Mizuho Securities Co., Ltd. (“MHSC”), Asset Management One Co., Ltd. (“Asset Management One”), and other subsidiaries. MHFG, through its subsidiaries (“the MHFG Group,” or “the Group”), provides domestic and international financial services in Japan and other countries. For a discussion of the Group’s segment information, see Note 30 “Business segment information.” MHFG and its domestic subsidiaries as well as its foreign subsidiaries maintain their accounting records in accordance with the accounting standards of Japan and those standards of the countries in which they are domiciled. Certain adjustments and reclassifications have been incorporated in the accompanying consolidated financial statements to conform them to the accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements are stated in Japanese yen, the currency of the country in which MHFG is incorporated and principally operates. The accompanying consolidated financial statements include the accounts of MHFG and its subsidiaries. MHFG’s fiscal year ends on March 31. MHFG’s subsidiaries fiscal year end is determined by each subsidiary. If the fiscal year end of a subsidiary has more than three months discrepancy from the MHFG’s fiscal year end, the subsidiary executes provisional financial closing. For those subsidiaries where the fiscal year end is not on March 31 and where the subsidiaries do not execute provisional financial close, the effect on the MHFG Group’s consolidated financial statements of all material events through the date of each of the periods presented in the consolidated financial statements has been considered for adjustment and/or disclosure. When determining whether to consolidate investee entities, the MHFG Group performs an analysis of the facts and circumstances of the particular relationships between the MHFG Group and the investee entities as well as the ownership of voting shares. The consolidated financial statements also include the accounts of VIEs for which MHFG or its subsidiaries have been determined to be the primary beneficiary in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 810, “Consolidation” (“ASC 810”). All significant intercompany transactions and balances have been eliminated upon consolidation. The MHFG Group accounts for investments in entities over which it has significant influence by using the equity method of accounting. These investments are included in Other investments and the Group’s proportionate share of income or loss is included in Equity in earnings (losses) of equity method investees—net. Certain comparative amounts for the prior period have been reclassified in order to conform to the current period’s presentation.
Use of estimates	Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts and related disclosures. Specific areas, among others, requiring the application of management’s estimates and judgment include assumptions pertaining to the allowance for credit losses, valuation of loans held-for-sale, valuation of deferred tax assets, valuation of derivative financial instruments, valuation of investments, valuation of certain long-term debt where the fair value option has been elected, valuation of pension and other employee benefits, and impairment of long-lived assets. During times of geopolitical unrest such as the situation in Russia and Ukraine and economic uncertainty such as elevated global inflation, estimates become more sensitive and it is reasonably possible that actual results could differ from estimates and assumptions made.
Definition of cash and cash equivalents	Definition of cash and cash equivalents For purposes of the consolidated statements of cash flows, Cash and cash equivalents consists of Cash and due from banks and Interest-bearing deposits in other banks. Cash deposited with central banks that must be maintained to meet minimum regulatory requirements is classified as restricted cash and included in Cash and cash equivalents. See Note 8 “Pledged assets and collateral” for more information on restricted cash.
Translation of foreign currency financial statements and foreign currency transactions	Translation of foreign currency financial statements and foreign currency transactions Financial statements of overseas entities are prepared using the functional currency of each entity and translated into Japanese yen for consolidation purposes. Assets and liabilities are translated using the fiscal-year-end Foreign currency translation gains and losses related to the financial statements of overseas entities of the MHFG Group, net of related income tax effects, are credited or charged directly to Foreign currency translation adjustments, a component of Accumulated other comprehensive income (loss), net of tax (“AOCI”). The tax effects of gains and losses related to the foreign currency translation of financial statements of overseas entities are not recognized unless it is apparent that the temporary differences will reverse in the foreseeable future. Assets and liabilities of domestic and overseas entities denominated in foreign currencies are remeasured into the functional currency of the respective entity at the fiscal year-end
Call loans and call money	Call loans and call money Call loans and call money represent lending/borrowing, primarily through the Japanese short-term money market, to/from other financial institutions such as banks, insurance companies, and securities brokerage houses.
Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions	Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions Securities sold under agreements to repurchase (“repurchase agreements”), securities purchased under agreements to resell (“resale agreements”) and securities lending and borrowing transactions are accounted for as secured financing or lending transactions when control over the underlying securities is not deemed to be surrendered by the transferor. Otherwise, they are recorded as sales of securities with related forward repurchase commitments or purchases of securities with related forward resale commitments in accordance with ASC 860, “Transfers and Servicing” (“ASC 860”). Under resale agreements, securities borrowing and certain derivatives transactions, the MHFG Group receives collateral in the form of securities. In many cases, the MHFG Group is permitted to sell or repledge the securities obtained as collateral. Disclosures in respect of such collateral are presented in Note 8 “Pledged assets and collateral.” With respect to repurchase agreements, securities lending, and certain derivative transactions, counterparties may have the right to sell or repledge securities that the MHFG Group has pledged as collateral. The MHFG Group separately discloses these pledged securities in the consolidated balance sheets. The MHFG Group monitors credit exposure arising from resale agreements, repurchase agreements, securities borrowing and securities lending transactions on a regular basis, and additional collateral is obtained from or returned to counterparties, as appropriate.
Trading securities and trading securities sold, not yet purchased	Trading securities and trading securities sold, not yet purchased Trading securities consist of securities and money market instruments that are bought and held principally for the purpose of reselling in the near term with the objective of generating profits on short-term fluctuations in price. Trading securities sold, not yet purchased, are securities and money market instruments sold to third parties that the MHFG Group does not own and is obligated to purchase at a later date to cover the short position. Trading securities and trading securities sold, not yet purchased, are recorded on the trade date. Trading securities and trading securities sold, not yet purchased, are recorded at fair value in the consolidated balance sheets in Trading account assets and Trading account liabilities with realized and unrealized gains and losses recorded on a trade date basis in Trading account gains (losses)—net in the consolidated statements of income. Interest and dividends on trading securities, including securities sold, not yet purchased, are recorded in Interest and dividend income or Interest expense on an accrual basis.
Investments	Investments Debt securities that the MHFG Group has both the positive intent and ability to hold to maturity are classified as Held-to-maturity Available-for-sale At the end of each reporting period the MHFG Group performs a review to identify impaired available-for-sale available-for-sale first-in first-out Other investments include marketable and non-marketable non-marketable
Derivative financial instruments	Derivative financial instruments Derivative financial instruments are bought and held principally for the purpose of market making for customers, proprietary trading in order to generate trading revenues and fee income, and also to manage the MHFG Group’s exposure to interest rate, credit and market risks related to asset and liability management. Such derivative financial instruments include interest rate, foreign currency, equity, commodity and credit default swap agreements, options, caps and floors, and financial futures and forward contracts. Derivatives bought and held for trading purposes are recorded in the consolidated balance sheets at fair value in Trading account assets and Trading account liabilities. The fair values of derivatives in a gain position and a loss position are reported as Trading account assets and Trading account liabilities, respectively. Derivatives used for asset and liability management include contracts that qualify for hedge accounting under ASC 815, “Derivatives and Hedging” (“ASC 815”). To be eligible for hedge accounting, derivative instruments must be highly effective in achieving offsetting changes in fair values or variable cash flows of the hedged items attributable to the particular risk being hedged. All qualifying hedging derivatives are valued at fair value and included in Trading account assets or Trading account liabilities. Derivatives that do not qualify for hedge accounting under ASC 815 are treated as trading positions and are accounted for as such. The fair value amounts recognized for all derivatives are presented on a gross basis and not offset against the amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under the master netting agreement with the same counterparty. The fair values of derivative financial instruments are determined based on quoted market prices or broker-dealer quotes, if available. If not available, the fair values are estimated using quoted market prices for similar instruments, option or binomial pricing models or a present value cash flow analysis, utilizing current observable market information, where available. In determining the fair values, the Group considers various factors such as exchange or over-the-counter Changes in the fair values of all derivatives are recorded in earnings, except for derivatives qualifying as net investment hedges under ASC 815 which are recorded in AOCI. The changes in the fair values of all derivatives relating to foreign currency exchange rates are included in Foreign exchange gains (losses)—net and Trading account gains (losses)—net. Other elements of the changes in the fair values, including interest rate, equity and credit related components, except these of certain credit derivatives hedging the credit risk in the corporate loan portfolio, are recognized in Trading account gains (losses)—net. The net gain (loss) resulting from changes in the fair values of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure related to its corporate loan portfolio is recorded in Other noninterest income (expenses). Certain financial and hybrid instruments often contain embedded derivative instruments that possess implicit or explicit contract terms similar to those of a derivative instrument. Such derivative instruments are required to be fair-valued separately from the host contracts if they meet the bifurcation criteria of an embedded derivative. Such criteria include that the entire instrument is not marked to market through earnings, the economic characteristics and risks of the embedded contract terms are not clearly and closely related to those of the host contract and the embedded contract terms would meet the definition of a derivative on a stand-alone basis.
Loans	Loans Loans are generally carried at the principal amount adjusted for unearned income and deferred net nonrefundable loan fees and costs. Loan origination fees, net of certain direct origination costs, are deferred and recognized over the contractual life of the loan as an adjustment of yield using a method that approximates the interest method. Interest income on performing loans is accrued and credited to income as it is earned. Unearned income and discounts or premiums on purchased loans are deferred and recognized over the life of the loan using a method that approximates the interest method. Loans are considered nonaccrual when, based on current information and events, it is probable that the MHFG Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. Factors considered by management in determining if a loan is nonaccrual include delinquency status and the ability of the debtor to make payments of the principal and interest when due. Nonaccrual loans include loans past due for 90 days or more and restructured loans that meet the definition of a troubled debt restructuring (“TDR”) in accordance with ASC 310, “Receivables” (“ASC 310”). The majority of nonaccrual loans have no contractual delinquency due to interest reductions and/or postponement of principal and interest. In case loans are designated as nonaccrual loans, interest accruals and the amortization of net origination fees are suspended and capitalized interest is written off. Cash received on nonaccrual loans is accounted for as a reduction of the loan principal if the ultimate collectability of the principal amount is in doubt, otherwise, as interest income. Loans are not restored to accrual status until interest and principal payments are current and future payments are reasonably assured. Nonaccrual loans are restored to accrual loans and accrual status, when the MHFG Group determines that the borrower poses no concerns regarding current certainty of debt fulfillment. In general, such determination is made if the borrower qualifies for an obligor rating of E2 or above and is not classified as a special attention obligor. With respect to loans restructured in a TDR, in general, such loans are restored to accrual loans, and accrual status, when the borrower qualifies for an obligor rating of D or above. See Note 4 “Loans” for the definitions of obligor ratings. Loans that have been identified for sale are classified as loans held for sale within Other assets and are accounted for at the lower of cost or fair value on an individual loan basis. If management decides to retain certain loans held for sale for the foreseeable future or until maturity or payoff, such items are transferred to Loans at the lower of cost or fair value.
Financial instruments—current expected credit losses ("CECL")	Financial instruments—current expected credit losses (“CECL”) CECL established a single allowance framework for all financial assets measured at amortized cost and certain off-balance-sheet available-for-sale
Allowance and provision (credit) for credit losses on loans	Allowance and provision (credit) for credit losses on loans Effective April 1, 2020, the allowance for credit losses on loans is established for current expected credit losses on the MHFG Group’s loan portfolio in accordance with ASC 326. Additionally, as of April 1, 2020, the Group did not elect the fair value option for financial assets measured at amortized cost basis. Prior to April 1, 2020, the allowance for credit losses on loans was established based on an incurred loss model in accordance with ASC 310 and ASC 450, “Contingencies” (“ASC 450”). The MHFG Group makes adjustments to the allowance for credit losses on loans through Provision (credit) for credit losses in the consolidated statements of income in each reporting period. Loan principal that management judges to be uncollectible, based on detailed loan reviews and a credit quality assessment, is charged off against the allowance for credit losses on loans. In general, the Group charges off loans when the Group determines that the obligor should be classified as substantially bankrupt or bankrupt. See Note 4 “Loans” for the definitions of obligor categories. Obligors in the retail portfolio segment are generally determined to be substantially bankrupt when they are past due for more than six months, and as for obligors in the corporate portfolio segment, the Group separately monitors the credit quality of each obligor without using time-based triggers. The MHFG Group maintains an appropriate allowance for credit losses on loans to represent management’s estimate of the expected credit losses in the Group’s loan portfolio. Management evaluates the appropriateness of the allowance for credit losses on loans semi-annually. The allowance considers expected credit losses over the remaining expected lives of the applicable instruments. The expected life of each instrument is determined by considering expected prepayments, contractual terms and cancellation features. The allowance for credit losses involves significant judgments on a number of matters including expectations of future economic conditions, assignment of obligor ratings, valuation of collateral, and the development of qualitative adjustments. When determining expected credit losses, a single forward-looking macroeconomic scenario is considered over a reasonable and supportable forecast period. This forward-looking macroeconomic scenario is in line with the scenario used for the Group’s business plan. If the scenario does not reflect a sudden change in economic conditions adequately, adjustments may be made to the scenario. After the forecast period, the Group reverts to long-term historical loss experience with a certain graduated transition period, to estimate losses over the remaining lives of financial assets measured at amortized cost and certain off-balance-sheet In terms of the internal risk ratings, for the corporate portfolio segment, the credit quality review process and the credit rating process serve as the basis for determining the allowance for credit losses on loans. Through such processes loans are categorized into groups to reflect the probability of default, whereby the MHFG Group’s management assesses the ability of borrowers to service their debt, taking into consideration current financial information, ability to generate cash, historical payment experience, analysis of relevant industry segments and current trends. For the retail portfolio segment, the different categories of past due status of loans are primarily utilized in the credit quality review and the credit rating processes as the basis for determining the allowance for credit losses on loans. In general, the MHFG Group estimates expected credit losses collectively on the loans in the case of normal and watch obligors, considering the risk associated with a particular pool and the probability that the exposures within the pool will deteriorate or default. The allowance for credit losses on nonaccrual loans generally includes the allowance for those loans that were individually evaluated for expected credit losses. See Note 4 “Loans” for the definitions of obligor categories and classification of nonaccrual loans. The estimation of expected credit losses that are evaluated collectively begins with a quantitative calculation that considers the likelihood of the borrower changing delinquency status or moving from one obligor category or rating to another. The quantitative calculation covers expected credit losses over an instrument’s expected life and is estimated by applying credit loss factors to the MHFG Group’s estimated exposure at default. The credit loss factors incorporate the probability of default as well as the loss given default based on the historical loss rates. To supplement the historical loss data for overseas obligors, external credit ratings such as S&P are also used to calculate the probability of default. The model and inputs used to determine credit losses on loans that are evaluated collectively are analyzed on a periodic basis by comparing the estimated values with the actual results subsequent to the balance sheet date. The MHFG Group divides its overall portfolio into domestic and foreign portfolios and categorizes the domestic portfolio into four portfolio segments according to their risk profiles: corporate, retail, sovereign, and banks and financial institutions. The corporate portfolio segment consists of loans originated primarily by MHBK and MHTB, and includes mainly business loans such as those used for working capital and capital expenditure, as well as loans for which the primary source of repayment of the obligation is income generated by the relevant assets such as project finance, asset finance and real estate finance. The corporate portfolio segment is divided into two classes based on their risk characteristics: large companies, and small and medium-sized The retail portfolio segment consists mainly of residential mortgage loans originated by MHBK, and it is divided into two classes based on their risk characteristics: housing loan and others. For the retail portfolio segment, the Japanese unemployment rate is applied as a key factor. As it pertains to TDRs in the retail portfolio segment, the restructuring itself, as well as subsequent payment defaults, if any, are considered in determining obligor categories. Expected credit loss estimates also include consideration of expected cash recoveries on loans previously charged-off, The allowance recorded for individually evaluated loans is based on (1) the present value of expected future cash flows, after considering the restructuring effect and subsequent payment default with respect to TDRs, discounted at the loan’s initial effective interest rate, (2) the loan’s observable market price, or (3) the fair value of the collateral if the loan is collateral dependent. The collateral that the MHFG Group obtains for loans consists primarily of real estate. In obtaining the collateral, the Group evaluates the fair value of the collateral and its legal enforceability. The Group also performs subsequent re-evaluations The MHFG Group’s methodology for determining the appropriate allowance for credit losses on loans also considers the imprecision inherent in the methodologies used. As a result, the amounts determined under the methodologies described above could be adjusted by management to consider the potential impact of other qualitative factors which include, but are not limited to, imprecision in macroeconomic scenario assumptions and emerging risks related to changes in the environment that are affecting specific portfolio segments including segments impacted by the Russia-Ukraine situation. Considering internal and external factors affecting the credit quality of the portfolio, the Group incorporated the estimated impact of the Russia-Ukraine situation, elevated global inflation and other factors contributing to economic uncertainty into the macroeconomic scenario by using assumptions such as the future outlook of the business environment for specific portfolio segments and the current forecast for the growth rate of gross domestic product. In terms of the Russia-Ukraine situation, considering the country risk arising from the continued sanctions against Russia and the downgrading of their credit rating, the MHFG Group incorporated the estimated impact of the Russia-Ukraine situation into the macroeconomic scenario used for determining the allowance for credit losses on loans.
Allowance and provision (credit) for credit losses on off-balance-sheet instruments	Allowance and provision (credit) for credit losses on off-balance-sheet The MHFG Group maintains an allowance for credit losses on off-balance-sheet off-balance-sheet off-balance-sheet
Allowance and provision (credit) for credit losses on available-for-sale securities	Allowance and provision (credit) for credit losses on available-for-sale The MHFG Group performs periodic reviews to identify impaired securities in accordance with ASC 326. Available-for-sale available-for-sale available-for-sale available-for-sale available-for-sale
Premises and equipment	Premises and equipment Premises and equipment are stated at historical cost, and depreciation and amortization are recorded over the estimated useful lives of the assets, except for leasehold improvements, which are amortized over the shorter of the estimated useful lives of the assets or the lease term. Depreciation and amortization are principally computed in accordance with the straight-line method with respect to buildings and leasehold improvements and in accordance with the declining-balance method with respect to other premises and equipment. The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20 Regular repairs and maintenance costs that do not extend the estimated useful life of an asset are charged to expense as incurred. Upon sale or disposition of premises and equipment, the cost and related accumulated depreciation or amortization are removed from the accounts, and any gains or losses on disposal are included in Gains on disposal of premises and equipment or Occupancy expenses.
Impairment of long-lived assets	Impairment of long-lived assets The MHFG Group’s long-lived assets that are held for use are reviewed periodically for events or changes in circumstances that indicate possible impairment. The Group’s impairment review is based on an undiscounted cash flow analysis of a group of assets, combined with associated liabilities, at the lowest level for which identifiable cash flows exist. Impairment occurs when the carrying value of the asset group exceeds the future undiscounted cash flows that the asset group is expected to generate. When impairment is identified, the future cash flows are then discounted to determine the estimated fair value of the asset group and an impairment charge
Software	Software Internal and external costs incurred in connection with developing and obtaining software for internal use during the application development stage are capitalized. Such costs include salaries and benefits for employees directly involved with and who devote time to the project, to the extent such time is incurred directly on the internal use software project. The capitalization of software ceases when the software project has been substantially completed. The capitalized software is amortized on a straight-line basis over the estimated useful life, generally 5 to 10 years. Internal use software is reviewed for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable.
Goodwill	Goodwill Goodwill represents the excess of the total fair value of the acquired company, which consists of the consideration transferred, the fair value of any interest in the acquiree already held by the acquirer and the fair value of any noncontrolling interest in the acquiree over the fair value of net identifiable assets acquired at the date of acquisition in a business combination. The MHFG Group accounts for goodwill in accordance with ASC 350, “Intangibles—Goodwill and Other” (“ASC 350”). Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not amortized but is tested for impairment at least annually or more often if events or circumstances indicate there may be impairment. For both the annual and interim tests, the Group has the option to either (a) perform a quantitative impairment test or (b) first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, in which case the Group would perform the quantitative test. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value. The estimated fair value of the reporting units is derived based on valuation techniques that the Group believes market participants would use for each of the reporting units. The Group generally determines the estimated fair value by utilizing a discounted cash flow methodology or methodologies that incorporate price-to-book
Intangible assets	Intangible assets Intangible assets having definite useful lives are amortized over their estimated useful lives on either a straight-line basis or the method that reflects the pattern in which the economic benefits of the intangible assets are consumed. Intangible assets acquired in connection with the merger of MHSC and Shinko Securities Co., Ltd. (“Shinko”) and the integration of asset management functions of DIAM Co., Ltd. (“DIAM”), MHTB, Mizuho Asset Management Co., Ltd. (“MHAM”) and Shinko Asset Management Co., Ltd. (“Shinko Asset Management”) consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. Intangible assets having indefinite useful lives are not amortized and are subject to impairment tests. An impairment loss is recorded to the extent that the carrying amount of the indefinite-lived intangible asset exceeds its estimated fair value. For intangible assets subject to amortization, an impairment loss is recorded if the carrying amount is not recoverable and exceeds its estimated fair value.
Leases	Leases The MHFG Group, as a lessee, recognizes liabilities to make lease payments and right-of-use non-lease right-of-use right-of-use right-of-use right-of-use
Pension and other employee benefits	Pension and other employee benefits MHFG and certain subsidiaries sponsor pension plans which provide defined benefits to retired employees and other postretirement benefit plans, including severance indemnities. Severance indemnities are amounts payable to eligible employees upon termination of employment and are payable as a lump sum. Periodic expense and accrued liabilities are computed based on the actuarial present value of benefits, net of investment returns expected from plan assets and their fair values at the balance sheet date. Net periodic expense is charged to Salaries and employee benefits. Net actuarial gains and losses that arise from differences between actual experience and assumptions are generally amortized over the average remaining service period of participating employees if they exceed the corridor, which is defined as the greater of 10% of plan assets or the projected benefit obligation.
Stock-based compensation	Stock-based compensation MHFG, MHBK, MHTB and MHSC have stock options, in the form of stock acquisition rights, for directors (excluding the outside directors) and executive officers of the respective companies (hereinafter referred to collectively as the “Directors”). In this plan (“the MHFG Group’s Stock Plan”), 100 shares of MHFG common stock shall be issued or transferred upon exercise of each of the stock acquisition rights. The exercise price is 1 yen per share. The contractual term of the stock acquisition rights is 20 years. A holder may exercise the stock acquisition rights only after the date on which such holder loses the status as a Director of MHFG, MHBK, MHTB or MHSC. In May 2015, the MHFG Group discontinued the stock option program. Thereafter, the MHFG Group has not issued any new stock options. MHFG, MHBK, MHTB and MHSC have a responsibility-based stock compensation program for Directors (“Stock Compensation I”) and a performance-based stock compensation program for Directors (“Stock Compensation II”). MHFG and certain consolidated subsidiaries introduced both responsibility-based and performance-based stock compensation program for Operating Officers (“Stock Benefit”) in July 2021. For these programs, the stock-based compensation cost is determined based on the fair value of MHFG’s common stock as of grant date. The liability related to the cash-based compensation cost is remeasured at each reporting date based on the fair value of MHFG’s common stock. For Stock Compensation I, as the program is effectively vested on the grant date, the stock-based compensation cost is recognized on the grant date. For Stock Compensation II, the stock-based compensation costs are recognized evenly over the graded-vesting period, which is three years. For Stock Benefit, the stock-based compensation costs are recognized evenly over the vesting period, which is one year. Those Stock options and Stock Compensation plans did not have a material impact on the MHFG Group’s consolidated results of operations or financial condition.
Long-term debt	Long-term debt Premiums, discounts and issuance costs of long-term debt are amortized based on a method that approximates the interest method over the respective terms of the long-term debt.
Obligations under guarantees	Obligations under guarantees The MHFG Group provides customers with a variety of guarantees and similar arrangements, including standby letters of credit, financial and performance guarantees, credit protection, and liquidity facilities. The MHFG Group recognizes guarantee fee income over the guarantee period. The MHFG Group receives such a guarantee fee at the inception of the guarantee or in
Fair Value Measurements	Fair Value Measurements The MHFG Group carries certain of its financial assets and liabilities at fair value on a recurring basis. These financial assets and liabilities are primarily composed of trading account assets, trading account liabilities, available-for-sale non-recurring Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. In accordance with ASC 820, “Fair Value Measurement” (“ASC 820”), the Group classifies its financial assets and liabilities into the fair value hierarchy (Level 1, 2, and 3). See Note 26 “Fair value” for the detailed definition of each level. When determining fair value, the MHFG Group considers the principal or most advantageous market in which the Group would transact and considers assumptions that market participants would use when pricing the asset or liability. The Group maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. See Note 26 “Fair value” for descriptions of valuation methodologies used for its assets and liabilities by product.
Fee and commission income	Fee and commission income The MHFG Group recognizes revenue from contracts with customers in an amount that reflects the consideration to which the Group expects to be entitled in exchange for transferring control of a promised service. The timing of revenue recognition is dependent on whether the Group satisfies a performance obligation by transferring control of the service to a customer over time or at a point in time. Fee and commission income is presented exclusive of consumption taxes. The major components of fee and commission income are as follows. Securities-related business fees mainly consist of brokerage fees and commissions, and asset-based revenues. Brokerage fees and commissions mainly include fees earned from the execution of customer transactions and sales commissions of stocks, bonds and investment trusts. Brokerage fees and commissions are recognized at the point in time on transaction date. Asset-based revenues mainly include fees received from investment trust management companies in return for administration services, such as record keeping services, of investment trusts. The amounts of asset-based revenues are calculated based on customer’s net asset value and recognized over time in the period when the related service is provided. Deposit-related fees include service charges on consumer and commercial deposit accounts such as account transfer charges. Deposit-related fees are recognized at the point in time when the transactions occur or the related service is provided. Lending-related fees include fees for lending business such as commitment fees and arrangement fees. Remittance business fees include service charges for domestic and international funds transfers and collections. These fees are recognized at the point in time when the related service is provided. Asset management business fees consist of investment trust management fees and investment advisory fees for investment trusts. These fees are received from investment trusts in return for asset management services and/or investment advisory services on behalf of customers. The amounts of these fees are calculated based on a percentage of customer’s net asset value. These fees are recognized over time in the period when the management and/or advisory service is provided and the amount is fixed. Trust-related business fees consist of trust fees earned primarily through fiduciary asset management and administrative service and other trust-related fees. Fees for fiduciary asset management and administration services for corporate pension plans and investment funds are recognized at the point on creation of the trust or completion date specified in the contract, or over time in the period when the related service is provided. Other trust-related fees mainly include brokerage commissions of real estate property, sales commissions of beneficial interest in real estate trust, consulting fees of real estate property and charges for stock transfer agent services. These fees are mainly earned on a transaction basis and recognized at the point in time when the related service is provided or over time in the period when the related service is provided. Agency business fees mainly include administration service fees related to the MHFG Group’s agency business such as Japan’s principal public lottery program and revenues from standing proxy services related to stocks and others. These fees are recognized at the point in time when the related service is provided or over time in the period when the related service is provided. Fees for other customer services include various revenues such as sales commissions of life insurance, service charges for electronic banking, financial advisory fees, and service charges for software development. Sales commissions from life insurance sales are received from insurance companies in return for selling insurance products and recognized when the insurance product is sold to customers. Service charges for electronic banking are mainly monthly basic usage fees and recognized over the related transaction period. Financial advisory fees are received as consideration for services supporting market research and business strategy planning, which are recognized over time in the period when the related advisory service based on the contract is rendered. Service charges for software development are recognized over time according to the progress of the development.
Fee and commission expenses	Fee and commission expenses The principal items included in fee and commission expenses are fee and commission expenses for remittance services and brokerages fees paid for securities transactions. These expenses are generally recognized on an incurred basis.
Income taxes	Income taxes Income taxes are accounted for in accordance with ASC 740, “Income Taxes” (“ASC 740”). Deferred income taxes reflect the net tax effects of (1) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the corresponding amounts used for income tax purposes, and (2) operating loss and tax credit carryforwards. A valuation allowance is recorded for any portion of the deferred tax assets unless it is more likely than not that the deferred tax assets will be realized. Deferred income tax benefit or expense is recognized for the changes in the net deferred tax asset or liability between periods.
Earnings per common share	Earnings per common share Basic earnings per common share are computed by dividing net per share

Basis of presentation and sum_3

Basis of presentation and summary of significant accounting policies (Tables)	12 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Useful Lives of Premises and Equipment	The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20

Investments (Tables)

Investments (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities	The amortized cost, net of allowance for credit losses, gross unrealized gains and losses, and fair value of available-for-sale held-to-maturity Amortized (4)(5) Gross gains Gross losses Fair value (in millions of yen) 2022 Available-for-sale Debt securities: Japanese government bonds 25,191,315 5,794 38,379 25,158,730 Japanese local government bonds 421,557 254 2,165 419,646 U.S. Treasury bonds and federal agency securities 381,653 — 8,444 373,209 Other foreign government bonds 1,338,295 220 2,578 1,335,937 Agency mortgage-backed securities (1) 452,830 1,695 3,985 450,540 Residential mortgage-backed securities 58,246 194 312 58,128 Commercial mortgage-backed securities 848,568 5,437 214 853,791 Japanese corporate bonds and other debt securities 2,222,670 14,212 1,705 2,235,177 Foreign corporate bonds and other debt securities (2) 787,263 2,490 1,021 788,732 Total 31,702,397 30,296 58,803 31,673,890 Held-to-maturity Debt securities: Japanese government bonds 479,980 5,101 — 485,081 Agency mortgage-backed securities (3) 1,039,075 24 58,604 980,495 Total 1,519,055 5,125 58,604 1,465,576 Amortized (4)(5) Gross gains Gross losses Fair value (in millions of yen) 2023 Available-for-sale Debt securities: Japanese government bonds 16,483,722 3,067 37,496 16,449,293 Japanese local government bonds 560,093 198 5,628 554,663 U.S. Treasury bonds and federal agency securities 382,990 — 7,289 375,701 Other foreign government bonds 1,309,473 661 2,261 1,307,873 Agency mortgage-backed securities (1) 532,364 1,140 11,307 522,197 Residential mortgage-backed securities 48,257 71 866 47,462 Commercial mortgage-backed securities 856,708 5,157 451 861,414 Japanese corporate bonds and other debt securities 2,100,733 13,024 4,538 2,109,219 Foreign corporate bonds and other debt securities (2) 1,005,209 2,319 1,581 1,005,947 Total 23,279,549 25,637 71,417 23,233,769 Held-to-maturity Debt securities: Japanese government bonds 799,305 2,171 1,028 800,448 Agency mortgage-backed securities (3) 1,250,802 403 136,545 1,114,660 Total 2,050,107 2,574 137,573 1,915,108 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥450,507 million and ¥33 million, respectively, at March 31, 2022, and ¥522,166 million and ¥31 million, respectively, at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. (2) Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥247,762 million at March 31, 2022, and ¥330,365 million at March 31, 2023. (3) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities. (4) Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale million at March 31, 2022, and ¥nil at March 31, 2023. (5) Accrued interest receivables are excluded from amortized cost, of which the amount were ¥4,702 million at March 31, 2022, and ¥5,637 million at March 31, 2023 and included in Accrued income.
Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity	The amortized cost, net of allowance for credit losses, and fair value of available-for-sale held-to-maturity Amortized cost Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 14,280,736 783,953 1,317,250 101,783 16,483,722 Japanese local government bonds 35,545 275,695 241,350 7,503 560,093 U.S. Treasury bonds and federal agency securities 382,990 — — — 382,990 Other foreign government bonds 1,027,119 279,985 1,186 1,183 1,309,473 Agency mortgage-backed securities — — 1,118 531,246 532,364 Residential mortgage-backed securities — — — 48,257 48,257 Commercial mortgage-backed securities 1,986 538,136 315,886 700 856,708 Japanese corporate bonds and other debt securities 412,207 1,155,415 240,446 292,665 2,100,733 Foreign corporate bonds and other debt securities 552,628 279,007 154,678 18,896 1,005,209 Total 16,693,211 3,312,191 2,271,914 1,002,233 23,279,549 Held-to-maturity Debt securities: Japanese government bonds 279,982 189,984 329,339 — 799,305 Agency mortgage-backed securities — — — 1,250,802 1,250,802 Total 279,982 189,984 329,339 1,250,802 2,050,107 Fair value Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 14,282,254 782,278 1,290,250 94,511 16,449,293 Japanese local government bonds 35,551 275,371 236,653 7,088 554,663 U.S. Treasury bonds and federal agency securities 375,701 — — — 375,701 Other foreign government bonds 1,026,121 279,384 1,186 1,182 1,307,873 Agency mortgage-backed securities — — 1,113 521,084 522,197 Residential mortgage-backed securities — — — 47,462 47,462 Commercial mortgage-backed securities 1,989 540,069 318,645 711 861,414 Japanese corporate bonds and other debt securities 412,157 1,154,386 238,775 303,901 2,109,219 Foreign corporate bonds and other debt securities 552,946 278,975 154,033 19,993 1,005,947 Total 16,686,719 3,310,463 2,240,655 995,932 23,233,769 Held-to-maturity Debt securities: Japanese government bonds 280,980 190,917 328,551 — 800,448 Agency mortgage-backed securities — — — 1,114,660 1,114,660 Total 280,980 190,917 328,551 1,114,660 1,915,108
Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position	The following table shows the gross unrealized losses, net of allowance for credit losses, and fair value of available-for-sale Less than 12 months 12 months or more Total Fair value Gross unrealized losses Fair value Gross unrealized losses Fair value Gross unrealized losses (in millions of yen) 2022 Available-for-sale Debt securities: Japanese government bonds 19,407,878 11,377 1,565,950 27,002 20,973,828 38,379 Japanese local government bonds 229,562 1,277 136,733 888 366,295 2,165 U.S. Treasury bonds and federal agency securities 321,073 7,209 41,555 1,235 362,628 8,444 Other foreign government bonds 729,134 2,178 71,647 400 800,781 2,578 Agency mortgage-backed securities (Note) 183,150 2,326 78,717 1,659 261,867 3,985 Residential mortgage-backed securities 9,221 11 17,193 301 26,414 312 Commercial mortgage-backed securities 58,815 185 13,939 29 72,754 214 Japanese corporate bonds and other debt securities 605,067 1,516 53,020 189 658,087 1,705 Foreign corporate bonds and other debt securities 302,569 692 53,338 329 355,907 1,021 Total 21,846,469 26,771 2,032,092 32,032 23,878,561 58,803 2023 Available-for-sale Debt securities: Japanese government bonds 3,706,134 11,369 1,419,222 26,127 5,125,356 37,496 Japanese local government bonds 146,484 1,596 322,224 4,032 468,708 5,628 U.S. Treasury bonds and federal agency securities 65,288 765 293,149 6,524 358,437 7,289 Other foreign government bonds 475,493 674 250,130 1,587 725,623 2,261 Agency mortgage-backed securities (Note) 142,776 2,361 238,858 8,946 381,634 11,307 Residential mortgage-backed securities 16,230 265 22,017 601 38,247 866 Commercial mortgage-backed securities 105,346 304 43,653 147 148,999 451 Japanese corporate bonds and other debt securities 1,177,725 3,775 635,289 763 1,813,014 4,538 Foreign corporate bonds and other debt securities 434,339 1,279 68,959 302 503,298 1,581 Total 6,269,815 22,388 3,293,501 49,029 9,563,316 71,417 Note: Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥261,867 million at March 31, 2022, and ¥381,634 million at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
Realized Gains and Losses on Sales of Available-for-Sale Securities	The following table shows the realized gains and losses on sales of available-for-sale 2021 2022 2023 (in millions of yen) Gross realized gains 3,309 12,540 22,962 Gross realized losses (24,407 ) (40,077 ) (23,593 ) Net realized gains (losses) on sales of available-for-sale (21,098 ) (27,537 ) (631 )
Summary of Details of Net Gains and Losses on Equity Securities	The following table shows the details of the net gains and losses on Equity securities for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Net gains (losses) recognized during the period on equity securities 850,567 (60,563 ) 135,601 Less: Net gains (losses) recognized during the period on equity securities sold during the period 82,969 17,000 29,561 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting 767,598 (77,563 ) 106,040
Summary of Equity Securities Without Readily Determinable Fair Values	The following table shows amounts recognized in earnings during the period due to downward adjustments and impairments and upward adjustments for equity securities without readily determinable fair values. 2021 2022 2023 (in millions of yen) Downward adjustments and impairments 3,084 2,626 1,291 Upward adjustments 404 2,459 1,459
Summary of Downward Adjustments and Impairments and Upward Adjustments	The following table shows carrying amounts of equity securities without readily determinable fair values, for which the measurement alternative is used, and cumulative amounts due to downward adjustments and impairments and upward adjustments, at March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Carrying amounts at the end of the period 186,146 207,407 207,743 Downward adjustments and impairments 5,087 6,519 5,345 Upward adjustments 9,216 11,623 13,015
Summary of Composition of Other Investments	The following table summarizes the composition of Other investments at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Equity method investments 519,552 598,772 Investments held by consolidated investment companies and other 62,836 68,429 Total 582,388 667,201

Loans (Tables)

Loans (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Credit Quality Information of Loans Based on MHFG Group's Internal Rating System	The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2022 and 2023: Term loans by origination year 2021 2020 2019 2018 2017 Prior to Revolving Loans Total (in billions of yen) 2022 Domestic: Corporate: Large companies: Normal obligors 12,236 6,641 5,049 4,535 1,679 3,379 7,155 40,674 Watch obligors excluding special attention obligors 146 69 71 66 40 51 128 571 Nonaccrual loans 61 101 201 45 136 77 178 799 Small and medium-sized Normal obligors 540 397 376 283 171 494 548 2,809 Watch obligors excluding special attention obligors 44 31 30 32 12 33 25 207 Nonaccrual loans 18 20 15 11 7 38 32 141 Retail: Housing Loan: Normal obligors 798 544 519 527 544 4,753 — 7,685 Watch obligors excluding special attention obligors 2 1 2 2 1 40 — 48 Nonaccrual loans 12 3 1 1 1 31 — 49 Others: Normal obligors 196 277 112 91 61 315 497 1,549 Watch obligors excluding special attention obligors 24 35 10 8 4 6 9 96 Nonaccrual loans 7 8 3 4 4 23 13 62 Sovereign: Normal obligors 938 106 89 109 55 352 2 1,651 Watch obligors excluding special attention obligors 4 4 1 — — — — 9 Nonaccrual loans — — — — — — — — Banks and other financial institutions: Normal obligors 46 24 132 211 — 144 125 682 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 15,072 8,261 6,611 5,925 2,715 9,736 8,712 57,032 Foreign: Corporate (4) Normal obligors 14,088 3,571 3,236 1,392 550 1,229 5,906 29,972 Watch obligors excluding special attention obligors 317 180 74 56 28 25 122 802 Nonaccrual loans 35 2 13 17 15 23 10 115 Retail: Normal obligors 2 2 2 1 1 3 — 11 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 279 7 33 15 174 3 75 586 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — 1 — — — — 1 Banks and other financial institutions: Normal obligors 1,003 254 151 225 12 1 120 1,766 Watch obligors excluding special attention obligors 5 — — — — — — 5 Nonaccrual loans 1 — — — — — — 1 Total foreign 15,730 4,016 3,510 1,706 780 1,284 6,233 33,259 Total 30,802 12,277 10,121 7,631 3,495 11,020 14,945 90,291 Term loans by origination year 2022 2021 2020 2019 2018 Prior to Revolving Loans Total (in billions of yen) 2023 Domestic: Corporate: Large companies: Normal obligors 12,277 5,993 5,384 3,994 3,065 3,670 7,517 41,900 Watch obligors excluding special attention obligors 109 46 50 58 59 33 130 485 Nonaccrual loans 153 35 61 134 99 159 339 980 Small and medium-sized Normal obligors 551 301 285 248 221 571 531 2,708 Watch obligors excluding special attention obligors 45 16 26 16 18 28 20 169 Nonaccrual loans 26 7 16 9 8 27 29 122 Retail: Housing Loan: Normal obligors 711 570 476 468 478 4,723 — 7,426 Watch obligors excluding special attention obligors 1 2 1 2 1 35 — 42 Nonaccrual loans 8 2 2 1 1 25 — 39 Others: Normal obligors 184 87 226 80 64 297 484 1,422 Watch obligors excluding special attention obligors 22 6 21 5 4 5 8 71 Nonaccrual loans 9 4 6 2 4 20 10 55 Sovereign: Normal obligors 1,217 54 90 91 75 328 1 1,856 Watch obligors excluding special attention obligors 8 2 — — — — — 10 Nonaccrual loans — — — — — — — — Banks and other financial institutions: Normal obligors 107 17 23 134 155 114 95 645 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 15,428 7,142 6,667 5,242 4,252 10,035 9,164 57,930 Foreign: Corporate (4) Normal obligors 15,317 3,891 2,142 1,954 1,024 1,312 6,731 32,371 Watch obligors excluding special attention obligors 228 101 192 72 43 50 58 744 Nonaccrual loans 31 19 13 18 11 32 11 135 Retail: Normal obligors 2 1 1 1 1 3 — 9 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 160 188 7 32 5 2 83 477 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — 1 — — — 1 Banks and other financial institutions: Normal obligors 1,536 265 169 91 19 4 404 2,488 Watch obligors excluding special attention obligors 8 4 4 5 — — — 21 Nonaccrual loans — — — — — — — — Total foreign 17,282 4,469 2,528 2,174 1,103 1,403 7,287 36,246 Total 32,710 11,611 9,195 7,416 5,355 11,438 16,451 94,176 Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered nonaccrual. (2) The primary component of the retail portfolio segment is housing loans to individuals which obligor category is classified based on past due status. The trigger to reclassify obligors from normal obligors to watch obligors excluding special attention obligors is when the past due status is more than 30 days. (3) There were no significant revolving line of credit arrangements that converted to term loans during the fiscal year ended March 31, 2022 and 2023. (4) Corporate of foreign include d were at
Impaired Loans Information	The table below presents nonaccrual loans information at March 31, 2022 and 2023: Amortized cost (1) Interest income recognized (2) Nonaccrual loans with an allowance Nonaccrual loans without an allowance Total nonaccrual loans (in billions of yen) 2022 Domestic: Corporate: Large companies 784 16 800 9 Small and medium-sized 121 19 140 2 Retail: Housing Loan 27 22 49 1 Others 40 22 62 1 Total domestic 972 79 1,051 13 Foreign: Total foreign (3) 110 7 117 1 Total 1,082 86 1,168 14 2023 Domestic: Corporate: Large companies 961 19 980 16 Small and medium-sized 103 19 122 1 Retail: Housing Loan 22 17 39 1 Others 37 18 55 1 Total domestic 1,123 73 1,196 19 Foreign: Total foreign (3) 132 4 136 4 Total 1,255 77 1,332 23 Notes: (1) Amounts represent the outstanding balances of nonaccrual loans. The MHFG Group’s policy for placing loans in nonaccrual status corresponds to the Group’s definition of nonaccrual loans. (2) Amounts represent the amount of interest income on nonaccrual loans recognized on a cash basis and included in Interest income on loans in the consolidated statements of income. (3) The majority of total foreign consist of corporate.
Troubled Debt Restructurings Entered Modified Periods by Type of Concession Granted	The following table presents modified loans that were determined to be TDRs during the fiscal years ended March 31, 2022 and 2023: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in billions of yen) 2022 Domestic: Corporate: Large companies 6 23 612 Small and medium-sized — — 125 Retail: Housing Loan — — 8 Others — — 22 Total domestic 6 23 767 Foreign: Total foreign (2) — — 63 Total 6 23 830 2023 Domestic: Corporate: Large companies — 141 595 Small and medium-sized — — 106 Retail: Housing Loan — — 5 Others — — 19 Total domestic — 141 725 Foreign: Total foreign (2) — — 66 Total — 141 791 Notes: (1) Amounts represent the book values of loans immediately after the restructurings. (2) The majority of total foreign consist of corporate.
Payment Defaults Occurred During Periods with Respect to Loans Modified as Troubled Debt Restructurings within Previous Twelve Months	The following table presents payment defaults which occurred during the fiscal years ended March 31, 2022 and 2023 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment 2022 2023 (in billions of yen) Domestic: Corporate: Large companies 8 95 Small and medium-sized 3 1 Retail: Housing Loan 1 1 Others 1 1 Total domestic 13 98 Foreign: Total foreign 14 10 Total 27 108
Age Analysis of Past Due Loans	The table below presents an analysis of the age of the amortized cost basis in loans that are past due at March 31, 2022 and 2023: 30-59 days past due 60-89 days past due 90 days or more past due Total past due Current Total (in billions of yen) 2022 Domestic: Corporate: Large companies — — 27 27 42,017 42,044 Small and medium-sized 1 1 10 12 3,145 3,157 Retail: Housing Loan 15 8 17 40 7,742 7,782 Others 5 1 11 17 1,690 1,707 Sovereign — — — — 1,660 1,660 Banks and other financial institutions — — — — 682 682 Total domestic 21 10 65 96 56,936 57,032 Foreign: Total foreign (Note) — — 29 29 33,230 33,259 Total 21 10 94 125 90,166 90,291 2023 Domestic: Corporate: Large companies — 3 28 31 43,334 43,365 Small and medium-sized — — 9 9 2,990 2,999 Retail: Housing Loan 14 8 13 35 7,472 7,507 Others 4 1 10 15 1,533 1,548 Sovereign — — — — 1,866 1,866 Banks and other financial institutions — — — — 645 645 Total domestic 18 12 60 90 57,840 57,930 Foreign: Total foreign (Note) — — 23 23 36,223 36,246 Total 18 12 83 113 94,063 94,176 Note: The majority of total foreign consist of corporate.

Allowance for Credit Losses o_2

Allowance for Credit Losses on Loans (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Changes in Allowance for Loan Losses, Allowance for Loan Losses and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment	Changes in Allowance for credit losses on loans by portfolio segment for the fiscal years ended March 31, 2021, 2022 and 2023 are shown below: Domestic Corporate Retail Sovereign Banks and Foreign (2) Total (in millions of yen) 2021 Balance at beginning of fiscal year 305,458 23,219 88 1,514 110,576 440,855 April 1, 2020 adoption of CECL 63,500 74,014 79 705 17,457 155,755 Adjusted balance at beginning of fiscal year 368,958 97,233 167 2,219 128,033 596,610 Provision (credit) for credit losses on loans 143,766 (8,558 ) (99 ) (1,596 ) (20,737 ) 112,776 Charge-offs (33,625 ) (6,802 ) — — (38,374 ) (78,801 ) Recoveries 2,321 1,298 — — 10,316 13,935 Net charge-offs (31,304 ) (5,504 ) — — (28,058 ) (64,866 ) Others (1) — — — — 6,329 6,329 Balance at end of fiscal year 481,420 83,171 68 623 85,567 650,849 2022 Balance at beginning of fiscal year 481,420 83,171 68 623 85,567 650,849 Provision (credit) for credit losses on loans 144,998 (6,895 ) (6 ) (227 ) 49,729 187,599 Charge-offs (3) (32,530 ) (4,166 ) — — (23,144 ) (59,840 ) Recoveries 7,618 1,304 — — 9,832 18,754 Net charge-offs (24,912 ) (2,862 ) — — (13,312 ) (41,086 ) Others (1) — — — 42 12,413 12,455 Balance at end of fiscal year 601,506 73,414 62 438 134,397 809,817 2023 Balance at beginning of fiscal year 601,506 73,414 62 438 134,397 809,817 Provision (credit) for credit losses on loans 51,551 (5,413 ) (9 ) 432 44,287 90,848 Charge-offs (3) (153,014 ) (5,664 ) — — (68,772 ) (227,450 ) Recoveries 5,858 1,204 — — 3,414 10,476 Net charge-offs (147,156 ) (4,460 ) — — (65,358 ) (216,974 ) Others (1) — — — — 17,268 17,268 Balance at end of fiscal year 505,901 63,541 53 870 130,594 700,959 Notes: (1) Others includes primarily foreign exchange translation. (2) The majority of total foreign consist of corporate. (3) Charge-offs increased from ¥ 59,840 for the fiscal year ended March 31, 2022 227,450 million for the fiscal year ended March 31, 2023 due mainly to a debt waiver to a domestic corporate borrower .

Premises and equipment (Tables)

Premises and equipment (Tables)	12 Months Ended
	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Summary of Premises and Equipment	Premises and equipment at March 31, 2022 and 2023 consist of the following: 2022 2023 (in millions of yen) Land 571,837 577,755 Buildings 737,440 703,655 Equipment and furniture 373,825 378,015 Leasehold improvements 208,820 204,835 Construction in progress 21,737 44,393 Software 1,373,035 1,366,445 Total 3,286,694 3,275,098 Less: Accumulated depreciation and amortization 1,582,627 1,621,210 Premises and equipment—net 1,704,067 1,653,888

Goodwill and intangible assets

Goodwill and intangible assets (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Changes in Goodwill	The changes in Goodwill during the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) Balance at beginning of fiscal year 92,997 92,695 92,695 Goodwill acquired — — 233 Impairment losses recognized (302 ) — — Balance at end of fiscal year 92,695 92,695 92,928 Gross amount of goodwill (Note) 167,552 161,993 163,209 Accumulated impairment losses 74,857 69,298 70,281 Note: Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not allocated to the reportable segments in Note 30 “Business segment information.”
Gross Carrying Amount, Accumulated Amortization and Net Carrying Amount of Intangible Assets	The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2022 and 2023: 2022 2023 Gross carrying amount Accumulated amortization Net carrying amount Gross carrying amount Accumulated amortization Net carrying amount (in millions of yen) Intangible assets subject to amortization: Customer relationships (Note) 126,979 87,277 39,702 130,124 94,777 35,347 Other 1,468 1,237 231 2,883 1,408 1,475 Total 128,447 88,514 39,933 133,007 96,185 36,822 Intangible assets not subject to amortization: Total 8,006 — 8,006 7,859 — 7,859 Total 136,453 88,514 47,939 140,866 96,185 44,681 Note: Customer relationships were mainly acquired in connection with the merger of MHSC and Shinko on May 7, 2009 and the integration among asset management companies on October 1, 2016. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information.
Estimated Aggregate Amortization Expense in Respect of Intangible Assets	The table below presents the estimated aggregate amortization expense in respect of intangible assets for the next five years: (in millions of yen) Fiscal year ending March 31: 2024 7,210 2025 6,698 2026 6,194 2027 5,564 2028 2,559

Pledged assets and collateral (

Pledged assets and collateral (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Amounts Pledged as Collateral for Borrowings and for Other Purposes	The following amounts, by balance sheet classification, have been pledged as collateral for 2022 2023 (in billions of yen) Interest-bearing deposits in other banks 75 92 Trading account assets 5,426 7,830 Investments 8,091 12,452 Loans 9,056 8,715 Other assets 3,023 2,059 Total 25,671 31,148
Associated Liabilities Collateralized by Pledged Assets	The associated liabilities collateralized by the above assets at March 31, 2022 and 2023 are summarized below: 2022 2023 (in billions of yen) Deposits 910 988 Payables under repurchase agreements 5,864 10,542 Payables under securities lending transactions 645 721 Other short-term borrowings 5,113 1,003 Long-term debt 542 2,173 Total 13,074 15,427

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Balance and Remaining Maturities of Time Deposits and Certificates of Deposit Issued by Domestic and Foreign Offices	The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2023 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 18,355,950 6,056,971 24,412,921 Due after one year through two years 1,376,534 174,580 1,551,114 Due after two years through three years 976,153 500 976,653 Due after three years through four years 240,172 — 240,172 Due after four years through five years 314,567 — 314,567 Due after five years 219,492 — 219,492 Total 21,482,868 6,232,051 27,714,919 Foreign offices: Due in one year or less 22,436,741 7,185,063 29,621,804 Due after one year through two years 25,120 281,524 306,644 Due after two years through three years 15,999 89,710 105,709 Due after three years through four years 23,404 — 23,404 Due after four years through five years 160 — 160 Due after five years 1,421 — 1,421 Total 22,502,845 7,556,297 30,059,142 Total 43,985,713 13,788,348 57,774,061
Estimated amounts of uninsured time deposits and certificates of deposit issued by domestic and foreign offices	The aggregate estimated amounts of time deposits and certificates of deposit that meet or exceed insurance limit issued by domestic and foreign offices at March 31, 2022 and 2023 are shown in the following table: 2022 2023 (in billions of yen) Domestic offices: Time deposits 10,437 13,977 Certificates of deposit 10,448 6,232 Total 20,885 20,209 Foreign offices: Time deposits 18,505 22,503 Certificates of deposit 6,421 7,556 Total 24,926 30,059

Short-term borrowings and lon_2

Short-term borrowings and long-term debt (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Details of Other Short-Term Borrowings	Details of Other short-term borrowings at March 31, 2022 and 2023 are as follows: 2022 2023 (in millions of yen) Short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) 46,668 41,142 Commercial paper and short-term notes issued by MHFG’s subsidiaries (1) (2) 2,266,360 2,218,111 Borrowings from the Bank of Japan 5,105,225 876,036 Other 148,518 262,040 Total 7,566,771 3,397,329 Notes: (1) Short-term notes are issued under the laws of Japan in the form of commercial paper. (2) The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥1,775,860 million and ¥490,500 million, respectively, at March 31, 2022, and ¥1,782,111 million and ¥436,000 million, respectively, at March 31, 2023.
Long-Term Debt with Original Maturities of More than One Year	Long-term debt with original maturities of more than one year at March 31, 2022 and 2023 is comprised of the following: 2022 2023 (in millions of yen) Obligations unde 4,621 6,863 Loan participation borrowings 220,312 245,176 Senior borrowings and bonds 8,600,493 11,245,475 Subordinated borrowings and bonds 3,752,790 3,395,509 Total 12,578,216 14,893,023
Interest Rates and Maturities of Senior Borrowings and Bonds, and Subordinated Borrowings and Bonds	The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2022 2023 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-6.20 Apr.2023 Jun.2051 1,032,194 2,819,085 fixed rate denominated in U.S. dollars 0.00-5.75 Apr.2023 Mar.2048 3,581,901 3,692,271 fixed rate denominated in other currencies 0.00-5.92 Apr.2023 May.2041 1,223,991 1,948,714 floating rate denominated in Japanese yen 0.00-25.00 Apr.2023 Sep.2081 582,430 569,173 floating rate denominated in U.S. dollars 0.00-32.80 Apr.2023 Feb.2068 2,001,616 2,058,714 floating rate denominated in other currencies 0.10-12.00 Apr.2023 Sep.2041 178,361 157,518 Total 8,600,493 11,245,475 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.39-4.26 Jun.2023 Perpetual 3,171,343 2,961,504 fixed rate denominated in U.S. dollars 2.56-4.70 Mar.2024 Sep.2031 581,447 434,005 Total 3,752,790 3,395,509 Total 12,353,283 14,640,984 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2023. (2) Maturity information disclosed is the range of maturities at March 31, 2023. (3) None of the long-term debt issuances above are convertible to common stock. (4) Certain debt agreements permit the MHFG Group to redeem the related debt, in whole or in part, prior to maturity at the MHFG Group’s option on terms specified in the respective agreements.
Contractual Maturities of Long-Term Debt	The following is a summary of contractual maturities of long-term debt subsequent to March 31, 2023: (in millions of yen) Fiscal year ending March 31: 2024 1,177,938 2025 3,757,328 2026 702,968 2027 1,428,227 2028 1,291,313 2029 and thereafter 6,535,249 Total 14,893,023

Other assets and liabilities (T

Other assets and liabilities (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Details of Other Assets and Liabilities	The following table sets forth the details of other assets and liabilities at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions 3,049,874 4,469,286 Other 557,842 468,344 Collateral pledged: Collateral pledged for derivative transactions 1,549,483 988,881 Margins provided for futures contracts 466,531 183,747 Other 1,006,849 890,350 Prepaid pension cost 762,147 768,998 Right-of-use 570,171 549,668 Security deposits 91,766 83,343 Loans held for sale 156,639 228,995 Other (1) 775,940 1,069,348 Total 8,987,242 9,700,960 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions 1,406,965 1,799,116 Other 494,538 527,493 Guaranteed trust principal (2) 810,776 817,448 Lease liabilities 593,339 571,087 Collateral accepted: Collateral accepted for derivative transactions 1,075,591 1,008,083 Margins accepted for futures contracts 327,883 81,925 Unearned income 113,181 112,077 Other 1,437,949 1,399,466 Total 6,260,222 6,316,695 Notes: (1) As of March 31, 2023, the MHFG Group included premises and equipment classified as held for sale in Other. (2) Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 23 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred stock (Tables)

Preferred stock (Tables)	12 Months Ended
	Mar. 31, 2023
Preferred stock
Statement [Line Items]
Schedule of Stock by Class	The composition of preferred stock at March 31, 2021, 2022 and 2023 is as follows: 2021 2022 2023 Class of stock Authorized Issued Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 90,000,000 — 90,000,000 — 90,000,000 — Class XV preferred stock 90,000,000 — 90,000,000 — 90,000,000 — Class XVI preferred stock 150,000,000 — 150,000,000 — 150,000,000 —

Common stock (Tables)

Common stock (Tables)	12 Months Ended
	Mar. 31, 2023
Common Stock
Statement [Line Items]
Schedule of Stock by Class	The following table shows the changes in the number of issued shares of common stock during the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (shares) Balance at beginning of fiscal year 2,539,249,894 2,539,249,894 2,539,249,894 Issuance of new shares of common stock due to exercise of stock acquisition rights — — — Balance at end of fiscal year 2,539,249,894 2,539,249,894 2,539,249,894

Accumulated other comprehensi_2

Accumulated other comprehensive income (loss), net of tax (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Changes in Each Component of AOCI	Changes in each component of AOCI for the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) AOCI, balance at beginning of fiscal year (9,494 ) 318,114 440,112 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year (19,592 ) (8,173 ) (25,046 ) Unrealized holding gains (losses) during year (4,911 ) (35,922 ) (7,472 ) Less: reclassification adjustments for losses (gains) included in net income 16,330 19,049 1,434 Change during year 11,419 (16,873 ) (6,038 ) Balance at end of fiscal year (8,173 ) (25,046 ) (31,084 ) Foreign currency translation adjustments: Balance at beginning of fiscal year (109,872 ) (86,873 ) 94,104 Foreign currency translation adjustments during year 22,704 181,722 133,556 Less: reclassification adjustments for losses (gains) included in net income 295 (745 ) — Change during year 22,999 180,977 133,556 Balance at end of fiscal year (86,873 ) 94,104 227,660 Defined benefit plan adjustments: Balance at beginning of fiscal year 69,455 397,153 355,355 Unrealized gains (losses) during year 331,668 (22,825 ) 86,326 Less: reclassification adjustments for losses (gains) included in net income (3,970 ) (18,973 ) (18,004 ) Change during year 327,698 (41,798 ) 68,322 Balance at end of fiscal year 397,153 355,355 423,677 Own credit risk adjustments Balance at beginning of fiscal year 50,515 16,007 15,699 Unrealized gains (losses) during year (30,345 ) (858 ) 12,688 Less: reclassification adjustments for losses (gains) included in net income (4,163 ) 550 755 Change during year (34,508 ) (308 ) 13,443 Balance at end of fiscal year 16,007 15,699 29,142 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 327,608 121,998 209,283 AOCI, balance at end of fiscal year 318,114 440,112 649,395
Amounts Reclassified Out of Accumulated Other Comprehensive Income into Net Income	The following table shows the amounts reclassified out of AOCI into net income during the fiscal year ended March 31, 2023: Before tax (1) Tax effect (2) Net of tax before allocation to noncontrolling interests Net of tax attributable to noncontrolling interests (2) Net of tax attributable to MHFG shareholders (in millions of yen) Amounts reclassified out of AOCI into net Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale (1,739 ) 305 (1,434 ) — (1,434 ) Investment gains (losses)—net Other noninterest income Defined benefit plan adjustments 25,840 (7,848 ) 17,992 12 18,004 Salaries and employee Own credit risk adjustments (1,089 ) 334 (755 ) — (755 ) Other noninterest income Total 23,012 (7,209 ) 15,803 12 15,815 Notes: (1) The financial statement line item in which the amounts in the before tax column are reported in the consolidated statements of income is listed to the right of the table. (2) The financial statement line items in which the amounts in the tax effect and the net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense (benefit) and Net income (loss), respectively.

Regulatory matters (Tables)

Regulatory matters (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Capital Requirements and Regulatory Adjustments Over Transitional Period	The capital requirements and regulatory adjustments are being phased in over a transitional period as follows: March 2022 March 2023 March 2024 March 2025 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % Capital conservation buffer 2.5 % 2.5 % 2.5 % 2.5 % Countercyclical capital buffer (1) 0.01 % 0.06 % 0.06 % 0.06 % Additional loss absorbency requirements for G-SIBs D-SIBs (2) 1.0 % 1.0 % 1.0 % 1.0 % Minimum Leverage Ratio 3.0 % 3.5 % (3) 3.5 % (3) 3.7 % (3) Notes: (1) Figures assume that the countercyclical capital buffer will continue to be 0.06% after March 2024. (2) Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB (3) This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB
Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency	Capital adequacy ratios and leverage ratios of MHFG, MHBK, and MHTB as of March 31, 2022 and 2023 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: 2022 2023 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (1) 5,184 8.01 5,676 8.06 Actual 8,067 12.46 8,315 11.80 Tier 1 capital: Required (1) 6,155 9.51 6,733 9.56 Actual 9,713 15.00 9,803 13.91 Total risk-based capital: Required (1) 7,450 11.51 8,142 11.56 Actual 11,351 17.53 11,306 16.05 Leverage Ratio (2) Required 6,389 3.00 7,680 3.50 (3) Actual 9,713 4.56 9,803 4.46 MHBK: Common Equity Tier 1 capital: Required 2,683 4.50 2,941 4.50 Actual 6,968 11.68 6,873 10.51 Tier 1 capital: Required 3,578 6.00 3,922 6.00 Actual 8,604 14.42 8,356 12.78 Total risk-based capital: Required 4,771 8.00 5,229 8.00 Actual 10,150 17.02 9,769 14.94 Leverage Ratio (2) Required 5,971 3.00 6,216 3.00 Actual 8,604 4.32 8,356 4.03 MHTB: Common Equity Tier 1 capital: Required 79 4.50 77 4.50 Actual 442 25.18 444 25.94 Tier 1 capital: Required 105 6.00 102 6.00 Actual 442 25.18 444 25.94 Total risk-based capital: Required 140 8.00 137 8.00 Actual 442 25.18 444 25.95 Leverage Ratio (2) Required 130 3.00 125 3.00 Actual 442 10.20 444 10.61 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,528 4.50 2,751 4.50 Actual 6,293 11.20 5,981 9.78 Tier 1 capital: Required 3,370 6.00 3,668 6.00 Actual 7,919 14.09 7,450 12.18 Total risk-based capital: Required 4,494 8.00 4,891 8.00 Actual 9,483 16.88 8,853 14.48 Leverage Ratio (2) Required 5,570 3.00 5,767 3.00 Actual 7,919 4.26 7,450 3.87 2022 2023 Amount Ratio Amount Ratio (in billions of yen, except percentages) MHTB: Common Equity Tier 1 capital: Required 78 4.50 76 4.50 Actual 425 24.40 425 25.10 Tier 1 capital: Required 104 6.00 101 6.00 Actual 425 24.40 425 25.10 Total risk-based capital: Required 139 8.00 135 8.00 Actual 425 24.40 425 25.11 Leverage Ratio (2) Required 126 3.00 122 3.00 Actual 425 10.09 425 10.44 Notes: (1) The required ratios disclosed above, at March 31, 2022, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01% and the additional loss absorbency requirements for G-SIBs D-SIBs %. The required ratios disclosed above, at March 31, 2023, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.06% and the additional loss absorbency requirements for G-SIBs and D-SIBs of 1.0%. These are all in addition to the regulatory minima. The respective required amounts are determined by applying the ratios to the sum of the risk weighted assets and certain other risk amounts. (2) The required and actual amounts disclosed above at March 31, 2022 and 2023 exclude amounts of deposits to the Bank of Japan. (3) The required ratio disclosed above, at March 31, 2023, includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB under the finalized Basel III reforms.

Earnings per common share (Tabl

Earnings per common share (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Computation of Basic and Diluted Earnings Per Common Share	The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Net income (loss): Net income (loss) attributable to MHFG common shareholders 581,765 (104,722 ) (14,009 ) Effect of dilutive securities — — — Net income (loss) attributable to common shareholders after assumed conversions 581,765 (104,722 ) (14,009 ) 2021 2022 2023 (thousands of shares) Shares: Weighted average common shares outstanding 2,537,513 2,537,051 2,536,596 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 89 — — Weighted average common shares after assumed conversions 2,537,602 2,537,051 2,536,596 2021 2022 2023 (in yen) Earnings per common share: Basic net income (loss) per common share 229.27 (41.28 ) (5.52 ) Diluted net income (loss) per common share (Note) 229.26 (41.28 ) (5.52 ) Note: For the fiscal years ended March 31, 2021, 2022 and 2023, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects. In addition, for the fiscal years ended March 31, 2022 and 2023, the computation of diluted earnings per common share did not assume exercise of stock options, as the effect of such exercise would be antidilutive due to net loss.

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Components of Income Tax Expense (Benefit)	The following table presents the components of Income tax expense (benefit) for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Current: Domestic 81,023 42,401 22,015 Foreign 78,992 71,947 156,969 Total current tax expense 160,015 114,348 178,984 Deferred: Domestic 55,927 (256,093 ) (146,721 ) Foreign (5,226 ) 728 2,879 Total deferred tax expense (benefit) 50,701 (255,365 ) (143,842 ) Total income tax expense (benefit) 210,716 (141,017 ) 35,142
Detailed Amounts of Tax Effects of Items Recorded Directly in Equity	The preceding table does not reflect the tax effects of items recorded directly in Equity for the fiscal years ended March 31, 2021, 2022 and 2023. The detailed amounts recorded directly in Equity are as follows: 2021 2022 2023 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) (2,810 ) (16,489 ) (4,276 ) Less: reclassification adjustments 7,195 8,504 305 Total 4,385 (7,985 ) (3,971 ) Defined benefit plan adjustments: Unrealized gains (losses) 143,653 (9,020 ) 37,661 Less: reclassification adjustments (1,424 ) (7,748 ) (7,848 ) Total 142,229 (16,768 ) 29,813 Own credit risk adjustments: Unrealized gains (losses) 919 1,745 5,630 Less: reclassification adjustments (1,911 ) 271 334 Total (992 ) 2,016 5,964 Total tax effect before allocation to noncontrolling interests 145,622 (22,737 ) 31,806
Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense	The following table shows a reconciliation of Income tax expense at the effective statutory tax rate to the actual income tax expense for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 Effective statutory tax rate 30.62 % 30.62 % 30.62 % Income not subject to tax (0.72 ) 4.21 (14.23 ) Expenses not deductible for tax purposes 0.07 (0.34 ) 1.63 Tax rate differentials of subsidiaries (0.90 ) 3.31 (12.95 ) Change in valuation allowance (3.83 ) (6.68 ) (2) (5.95 ) Change in undistributed earnings of subsidiaries 0.34 (2.22 ) 8.32 Noncontrolling interest income (loss) of consolidated VIEs (6.83 ) (2.10 ) (15.48 ) Effect of enacted change in tax rates (0.02 ) 0.01 (0.05 ) Reversal of outside basis differences — 50.59 (2) — Foreign tax credit and payments 0.16 (16.59 ) 55.14 Income excluded from taxable income of enterprise tax (0.49 ) 2.86 (14.96 ) Controlled foreign company rules 0.71 (1.66 ) 2.68 Other 1.37 (3.86 ) 16.04 Effective income tax rate 20.48 % 58.15 % 50.81 % Notes: (1) The presentation of the table is changed from from (2) These amounts for the fiscal year ended March 31, 2022 mainly represent the reversal of an outside basis difference related to the share buyback conducted by MHSC in response to improving the capital position and aligning to the MHFG Group’s capital policy and the related increase in the valuation allowance.
Components of Net Deferred Tax Assets	The components of net deferred tax assets at March 31, 2022 and 2023 are as follows: 2022 2023 (in millions of yen) Deferred tax assets: Allowance for credit losses 292,277 270,423 Lease liabilities 183,537 176,304 Trading securities 118,242 173,793 Derivative financial instruments 52,321 161,141 Premises and equipment 65,051 53,531 Available-for-sale 8,313 13,020 Net operating loss carryforwards (1) (2) 183,410 168,387 Other 223,564 255,557 1,126,715 1,272,156 Valuation allowance (1)(2) (163,164 ) (198,800 ) Deferred tax assets, net of valuation allowance 963,551 1,073,356 Deferred tax liabilities: Investments 213,398 264,147 Prepaid pension cost and accrued pension liabilities 221,256 224,173 Right-of-use 176,591 169,353 Other 104,020 54,515 Deferred tax liabilities 715,265 712,188 Net deferred tax assets 248,286 361,168 Notes: (1) The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income. (2) The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction	The following table and accompanying footnotes provide a breakdown of deferred tax assets and the valuation allowance recognized in respect of net operating loss carryforwards by tax jurisdiction and by year of expiration as of March 31, 2022 and 2023: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2022 Japan (1) 106 (77 ) 29 The United States 1 — 1 The United Kingdom (2) 75 (75 ) — Others 1 — 1 Total 183 (152 ) 31 2023 Japan (3) 89 (75 ) 14 The United States 1 — 1 The United Kingdom (2) 77 (77 ) — Others 1 — 1 Total 168 (152 ) 16 Notes: (1) ¥74 billion of the Japan deferred tax assets of ¥106 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥27 billion of the Japan deferred tax assets of ¥106 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes. (3) ¥49 billion of the Japan deferred tax assets of ¥89 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥25 billion of the Japan deferred tax assets of ¥89 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032.
Roll-forward Valuation Allowance	The following table presents a roll-forward of the valuation allowance for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Balance at beginning of fiscal year 165,278 129,150 163,164 Changes that directly affected Income tax expense (39,410 ) 16,196 (4,118 ) Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards — — — Others 3,282 17,818 39,754 Total 3,282 17,818 39,754 Balance at end of fiscal year 129,150 163,164 198,800
Net Operating Losses Carryforwards by Expiration Date	At March 31, 2023, the MHFG Group had net operating loss carryforwards totaling ¥500 billion. These carryforwards are scheduled to expire as follows: Net operating loss carryforwards (1) (in billions of yen) Fiscal year ending March 31: 2024 — 2025 — 2026 156 2027 3 2028 — 2029 and thereafter (2) 341 Total 500 Notes: (1) Net operating loss carryforwards related to Japanese local taxes recorded at MHFG in the fiscal year ended March 31, 202 2 mostly (2) Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom.
Roll-forward of Unrecognized Tax Benefits	The following table is a roll-forward of unrecognized tax benefits for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 3,374 4,401 5,245 Gross amount of increases (decreases) related to positions taken during prior 455 (576 ) (438 ) Gross amount of increases related to positions taken during the current year 524 954 1,748 Amount of decreases related to settlements — — — Foreign exchange translation 48 466 488 Total unrecognized tax benefits at end of fiscal year 4,401 5,245 7,043

Pension and other employee be_2

Pension and other employee benefit plans (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Components of Net Periodic Benefit Cost of Severance Indemnities and Pension Plans	The following table presents the components of net periodic benefit cost of the severance indemnities and pension plans for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Service cost-benefits earned during the fiscal year 39,672 33,190 30,460 Interest costs on projected benefit obligations 5,790 5,636 6,917 Expected return on plan assets (41,887 ) (37,051 ) (36,322 ) Amortization of prior service cost (benefits) (2,378 ) (4,820 ) (4,854 ) Amortization of net actuarial loss (gain) 1,671 (20,485 ) (19,453 ) Special termination benefits 9,569 10,791 7,269 Loss (gain) on settlement (3,945 ) — — Net periodic benefit cost 8,492 (12,739 ) (15,983 )
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) Before-Tax	Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2022 2023 (in millions of yen) Net actuarial gain (loss) (36,796 ) 122,331 Amortization of net actuarial loss (gain) (20,485 ) (19,453 ) Prior service benefits (cost) (1 ) — Amortization of prior service cost (benefits) (4,820 ) (4,854 ) Total recognized in other comprehensive income (loss) before-tax (62,102 ) 98,024
Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost	Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost are as follows: 2021 2022 2023 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.38 % 0.52 % 0.82 % Rates of increase in future compensation levels 1.80 % 2.00 % 2.00 % Interest credit rates 4.38 % 4.39 % 4.45 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.37 % 0.38 % 0.52 % Rates of increase in future compensation levels 1.80-4.80 % 1.80 % 2.00 % Expected rates of return on plan assets 1.79 % 1.54 % 1.72 % Interest credit rates 4.95 % 4.38 % 4.39 %
Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets	The following table sets forth the combined funded status and amounts recognized in the accompanying consolidated balance sheets at March 31, 2022 and 2023 for the plans of MHFG and its subsidiaries: 2022 2023 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,437,843 1,377,739 Service cost 33,190 30,460 Interest cost 5,636 6,917 Plan participants’ contributions 1,089 1,053 Amendments 1 — Actuarial loss (gain) (19,939 ) (48,856 ) Foreign exchange translation 4,099 3,250 Benefits paid (54,483 ) (55,332 ) Lump-sum (29,697 ) (27,539 ) Benefit obligations at end of fiscal year 1,377,739 1,287,692 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,412,745 2,114,011 Actual return (negative return) on plan assets (8,008 ) 92,893 Foreign exchange translation 3,863 3,158 Partial withdrawal of assets from employee retirement benefits (Note) (270,172 ) (147,181 ) Employer contributions 28,977 23,613 Plan participants’ contributions 1,089 1,053 Benefits paid (54,483 ) (55,332 ) Fair value of plan assets at end of fiscal year 2,114,011 2,032,215 Funded status 736,272 744,523 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 762,147 768,998 Accrued pension liability (25,875 ) (24,475 ) Net amount recognized 736,272 744,523 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) 63,030 58,173 Net actuarial gain (loss) 421,690 524,571 Net amount recognized 484,720 582,744 Note: During the fiscal year s severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2023. No gains or losses have been recognized as a result of these transactions.
Plans with Projected Benefit Obligations in Excess of Plan Assets and Plans with Accumulated Benefit Obligations in Excess of Plan Assets	The following table shows the projected benefit obligations and the fair value of plan assets for the plans of MHFG and its subsidiaries with projected benefit obligations in excess of plan assets, and the accumulated benefit obligations and the fair value of plan assets for the plans with accumulated benefit obligations in excess of plan assets at March 31, 2022 and 2023: 2022 2023 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 31,829 29,389 Fair value of plan assets 5,954 4,914 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 31,829 29,389 Fair value of plan assets 5,954 4,914 Note: The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets.
Target Allocation for Plan Assets Excluding those of Employee Retirement Benefit Trusts	MHFG and certain subsidiaries’ target allocation for the plan assets, excluding those of the employee retirement benefit trusts, at March 31, 2023 is as follows: Asset category Asset ratio Japanese equity securities 3.00 % Japanese debt securities 32.00 % Foreign equity securities 26.00 % Foreign debt securities 24.00 % General account of life insurance companies 10.00 % Other 5.00 % Total 100.00 % Note: General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments.
Fair Value of Plan Assets by Asset Category	The following table presents the fair value of plan assets of MHFG and its subsidiaries at March 31, 2022 and 2023, by asset class. For the detailed information on fair value measurements, including descriptions of Level 1, 2 and 3 of the fair value hierarchy and the valuation methodologies, see Note 26 “Fair value.” 2022 2023 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,003 — — 1,003 1,018 — — 1,018 Pooled funds (2) 13 5 — 18 5 6 — 11 Japanese debt securities: Government bonds 179 — — 179 123 — — 123 Pooled funds (2) — 10 — 10 — 8 — 8 Other — 21 — 21 — 21 — 21 Foreign equity securities: Common stocks 172 — — 172 94 — — 94 Pooled funds (2) — 7 — 7 — 8 — 8 Foreign debt securities: Government bonds 170 9 — 179 173 14 — 187 Pooled funds (2) — 10 — 10 — 3 — 3 Other — 18 — 18 — 15 — 15 General account of life insurance companies (3) — 116 — 116 — 113 — 113 Other 30 (4) (25 ) — 5 101 (4) 5 — 106 Plan assets measured at net asset value (5) 376 325 Total assets at fair value 1,567 171 — 2,114 1,514 193 — 2,032 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,003 billion and ¥1,018 billion carried at fair value at March 31, 2022 and 2023, respectively, which are well-diversified across industries. (2) These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request. (3) Investments in this class are measured at conversion value, which is equivalent to fair value. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.
Forecasted Benefit Payments Including Effect of Expected Future Service	The following table presents forecasted benefit payments including the effect of expected future service for the fiscal years indicated: (in millions of yen) Fiscal year ending March 31: 2024 82,311 2025 75,506 2026 75,992 2027 74,496 2028 76,348 2029-2033 330,309

Derivative financial instrume_2

Derivative financial instruments (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding	Fair value Derivative receivables (2) Derivative payables (2) 2022 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,395,950 — 4,624 — 4,716 Foreign exchange contracts 217,462 — 4,436 — 4,472 Equity-related contracts 9,887 — 426 — 345 Credit-related contracts 11,857 — 118 — 121 Other contracts 681 — 119 — 116 Total 1,635,837 — 9,723 — 9,770 Fair value Derivative receivables (2) Derivative payables (2) 2023 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,991,016 — 8,374 — 8,517 Foreign exchange contracts 257,392 — 4,222 — 4,013 Equity-related contracts 7,149 — 145 — 197 Credit-related contracts 22,748 — 144 — 126 Other contracts 898 — 47 — 43 Total 2,279,203 — 12,932 — 12,896 Notes: (1) Notional amount includes the sum of gross long and gross short third-party contracts. (2) Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively.
Summary of Notional and Fair Value Amounts of Credit Derivatives	The following table summarizes the notional and fair value amounts of credit derivatives at March 31, 2022 and 2023: 2022 2023 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 3,045 38 4,497 31 Non-investment 2,122 54 5,774 62 Total 5,167 92 10,271 93 Credit protection purchased 6,690 (95 ) 12,477 (75 ) Note: The rating scale is based upon either the external ratings or the internal ratings of the underlying reference credit. The lowest investment grade rating is considered to be BBB - non-investment Non-investment
Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period	The following table shows the maximum potential amount of future payments for credit protection written by expiration period at March 31, 2022 and 2023: Maximum payout/Notional amount 2022 2023 (in billions of yen) One year or less 245 331 After one year through five years 4,785 9,585 After five years 137 355 Total 5,167 10,271 Note: The maximum potential amount of future payments is the aggregate notional amount of the credit derivatives where the Group wrote the credit protection, and it has not been reduced by the effect of any amounts that the Group may possibly collect on the underlying assets and the related cash flows, nor netted against that of credit protection purchased.
Quantitative Information about Derivative Instruments with Credit-risk-related Contingent Features	The following table shows the quantitative information about derivative instruments with credit-risk-related contingent features at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 1,149 814 Collateral provided to counterparties in the normal course of business 1,164 663 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered — 151
Not Designated as Hedging Instrument
Statement [Line Items]
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes gains and losses on derivatives not designated or qualifying as hedges during the fiscal years ended March 31, 2021, 2022 and 2023: Gains (losses) recorded in income 2021 2022 2023 (in millions of yen) Interest rate contracts (27,893 ) (130,312 ) (508,743 ) Foreign exchange contracts 115,181 145,979 317,459 Equity-related contracts (209,488 ) 728,226 534,615 Credit-related contracts (Note) (58,602 ) (13,877 ) (3,857 ) Other contracts 23,680 7,762 59,599 Total (157,122 ) 737,778 399,073 Note: Amounts include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively.

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Summary of Maximum Potential Amount of Future Payments under Guarantees	The MHFG Group, when necessary, requires collateral such as cash, investment securities and real estate or third-party guarantees depending on the amount of credit risk involved, and employs means such as sub-participation 2022 Maximum potential/Contractual or Notional amount Amount by expiration period One year or After one year through five years After five years (in billions of yen) Performance guarantees 3,254 2,084 996 174 Guarantees on loans 419 314 42 63 Guarantees on securities 75 9 66 — Other guarantees 2,899 2,381 451 67 Guarantees for the repayment of trust principal 22 — 9 13 Liabilities of trust accounts 478 116 199 163 Derivative financial instruments 36,484 17,110 15,721 3,653 2023 Maximum potential/Contractual or Notional amount Amount by expiration period One year or After one year through five years After five years (in billions of yen) Performance guarantees 3,548 1,954 1,413 181 Guarantees on loans 228 149 26 53 Guarantees on securities 82 14 68 — Other guarantees 3,306 2,339 869 98 Guarantees for the repayment of trust principal 18 — 8 10 Liabilities of trust accounts 554 97 282 175 Derivative financial instruments 83,420 53,774 24,954 4,692
Summary of Contractual Amounts with Regard to Undrawn Commitments	The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Commitments to extend credit (Note) 92,203 100,973 Commercial letters of credit 1,422 1,336 Total 93,625 102,309 Note: Commitments to extend credit include commitments to invest in securities.
Schedule of Balance Sheet Information Related to operating lease	The following table presents the consolidated balance sheet information related to operating leases as of March 31, 2022 and 2023: 2022 2023 (in millions of yen, except for remaining lease Right-of-use (Note) 570,171 549,668 Lease liabilities (Note) 593,339 571,087 Weighted average: Remaining lease term 15.5 years 14.7 years Discount rate 0.60 % 0.66 % Note: Right-of-use
Schedule of operating lease cost and supplemental cash flow information	The following table presents lease cost and supplemental information related to operating leases for the fiscal years ended March 31, 2021, 2022 and 2023: 2021 2022 2023 (in millions of yen) Lease cost (Note) 119,453 111,907 101,808 Right-of-use 108,430 51,901 65,417 Operating cash flows 102,150 101,223 86,329 Note: Lease cost for operating leases are included in Occupancy expenses on the consolidated statements of income. The Group’s variable lease costs and costs for leases with terms of twelve months or less are not significant.
Future Minimum Lease Payments for Capitalized Leases and Rental Payments for Operating Leases	The following table shows future lease payments under operating leases as of March 31, 2023: As of March 31, 2023 (in millions of yen) Fiscal year ending March 31: 2024 79,207 2025 60,345 2026 53,518 2027 43,575 2028 34,048 2029 and thereafter 324,165 Total lease payments 594,858 Amount representing interest 23,771 Total lease liabilities for operating leases 571,087
Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees
Statement [Line Items]
Summary of Maximum Potential Amount of Future Payments under Guarantees	The table below presents the maximum potential amount of future payments of performance guarantees, guarantees on loans, guarantees on securities and other guarantees classified based on internal ratings at March 31, 2022 and 2023: 2022 2023 (in billions of yen) Investment grade 5,336 5,587 Non-investment 1,311 1,577 Total 6,647 7,164 Note: Investment grade in the internal rating scale generally corresponds to BBB-

Variable interest entities an_2

Variable interest entities and securitizations (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Schedule of Variable Interest Entities	The table below shows the consolidated assets of the Group’s consolidated VIEs as well as total assets and maximum exposure to loss for its significant unconsolidated VIEs, in which the Group has determined that its maximum exposure to loss is greater than specific thresholds or meets certain other criteria as of March 31, 2022 and 2023: Consolidated VIEs Significant unconsolidated VIEs 2022 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,709 — — Asset-backed securitizations 1,363 190 90 Investments in securitization products 388 — — Investment funds 1,816 3,392 719 Trust arrangements and other 5,299 — — Total 11,575 3,582 809 Consolidated VIEs Significant unconsolidated VIEs 2023 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 3,082 — — Asset-backed securitizations 1,514 224 134 Investments in securitization products 387 — — Investment funds 2,294 3,397 845 Trust arrangements and other 4,877 — — Total 12,154 3,621 979
Unconsolidated VIEs
Statement [Line Items]
Schedule of Variable Interest Entities	The tables below present the carrying amounts and classification of assets and liabilities on the MHFG Group’s balance sheets that relate to its variable interests in significant unconsolidated VIEs, as of March 31, 2022 and 2023: Assets on the MHFG Group’s balance sheets related to unconsolidated VIEs: 2022 2023 (in billions of yen) Trading account assets 143 83 Investments 430 482 Loans 92 154 Total 665 719 Liabilities on the MHFG Group’s balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2022 2023 (in billions of yen) Payables under securities lending transactions 54 — Trading account liabilities 2 1 Total 56 1 Maximum exposure to loss (Note) 809 979 Note: This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet off-balance-sheet

Noninterest income (Tables)

Noninterest income (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Summary of Noninterest Income	Details of Noninterest income for the fiscal years ended March 31, 2021, 2022 and 2023 are as follows: 2021 2022 2023 (in millions of yen) Fee and commission income: Securities-related business (1) 170,216 184,014 190,026 Deposits-related business (1) 15,162 15,358 15,540 Lending-related business (2) (4) 158,921 162,953 193,838 Remittance business (1) 109,111 103,979 104,201 Asset management business (1) 104,753 122,014 109,358 Trust-related business (1) 122,215 141,365 130,576 Agency business (1) 31,331 36,899 36,529 Guarantee-related business (3) 31,665 35,296 41,150 Fees for other customer services (1) 169,310 178,122 163,127 Total Fee and commission income 912,684 980,000 984,345 Foreign exchange gains (losses)—net (3) 89,267 91,611 189,526 Trading account gains (losses)—net (2) 120,596 (491,947 ) (603,910 ) Investment gains (losses)—net: Debt securities (3) (22,032 ) (14,777 ) 5,167 Equity securities (3) 850,567 (60,563 ) 135,601 Equity in earnings (losses) of equity method investees—net (3) 31,027 34,587 (26,999 ) Gains on disposal of premises and equipment (3) 7,125 9,943 4,920 Other noninterest income (2) (5) 52,086 120,936 199,453 Total 2,041,320 669,790 888,103 Notes: (1) These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers” (“ASC 606”). (2) Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606. (3) These amounts are revenues from contracts that do not meet the scope of ASC 606. (4) Most of the lending-related fees such as commitment fees and arrangement fees are not within the scope of ASC 606. (5) These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 26 “Fair value” for further details.

Trading account gains and los_2

Trading account gains and losses (Tables)	12 Months Ended
	Mar. 31, 2023
Trading Account Gains And Losses [Abstract]
Net Trading Gains and Losses	Net trading gains (losses) for the fiscal years ended March 31, 2021, 2022 and 2023 are comprised of the following: 2021 2022 2023 (in millions of yen) Trading account gains (losses)—net: Trading securities 274,762 (1,230,330 ) (1,003,636 ) Derivative contracts: Interest rate contracts (27,893 ) (130,312 ) (508,743 ) Foreign exchange contracts (1) 115,181 145,979 317,459 Equity-related contracts (209,488 ) 728,226 534,615 Credit-related contracts (2) (55,646 ) (13,272 ) (3,204 ) Other contracts 23,680 7,762 59,599 Total 120,596 (491,947 ) (603,910 ) Foreign exchange gains (losses)—net (3) 89,267 91,611 189,526 Net trading gains (losses) 209,863 (400,336 ) (414,384 ) Notes: (1) Amounts include gains and losses on currency swaps. (2) Amounts do not include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively. The net gains (losses) is recorded in Other noninterest income (expenses). (3) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.

Fair value (Tables)

Fair value (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected	Assets and liabilities measured at fair value on a recurring basis at March 31, 2022 and 2023, including those for which the MHFG Group has elected the fair value option, are summarized below: 2022 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,604 11 — 1,615 Japanese local government bonds — 145 — 145 U.S. Treasury bonds and federal agency securities 2,353 711 — 3,064 Other foreign government bonds 907 639 — 1,546 Agency mortgage-backed securities — 3,176 — 3,176 Residential mortgage-backed securities — — 8 8 Certificates of deposit and commercial paper — 640 — 640 Corporate bonds and other (2) 15 2,743 71 2,829 Equity securities 1,381 213 28 1,622 Trading securities measured at net asset value (3) 284 Derivative financial instruments: Interest rate contracts 89 4,513 22 4,624 Foreign exchange contracts — 4,404 32 4,436 Equity-related contracts 77 323 26 426 Credit-related contracts — 116 2 118 Other contracts 49 18 52 119 Available-for-sale Japanese government bonds 24,662 497 — 25,159 Japanese local government bonds — 420 — 420 U.S. Treasury bonds and federal agency securities 373 — — 373 Other foreign government bonds 363 973 — 1,336 Agency mortgage-backed securities — 451 — 451 Residential mortgage-backed securities — 40 18 58 Commercial mortgage-backed securities — 854 — 854 Japanese corporate bonds and other debt securities — 1,920 315 2,235 Foreign corporate bonds and other debt securities — 671 117 788 Equity securities: Equity securities with readily determinable fair values 3,094 61 — 3,155 Equity securities measured at net asset value (3) 210 Other investments 2 — 56 58 Total assets measured at fair value on a recurring basis 34,969 23,539 747 59,749 Liabilities: Trading securities sold, not yet purchased 3,054 2,035 — 5,089 Derivative financial instruments: Interest rate contracts 80 4,636 — 4,716 Foreign exchange contracts — 4,472 — 4,472 Equity-related contracts 122 183 40 345 Credit-related contracts — 120 1 121 Other contracts 28 36 52 116 Long-term debt (4) — 1,962 794 2,756 Total liabilities measured at fair value on a recurring basis 3,284 13,444 887 17,615 2023 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,187 7 — 1,194 Japanese local government bonds — 138 — 138 U.S. Treasury bonds and federal agency securities 1,917 1,377 — 3,294 Other foreign government bonds 658 786 — 1,444 Agency mortgage-backed securities — 5,309 — 5,309 Residential mortgage-backed securities — — — — Certificates of deposit and commercial paper — 516 — 516 Corporate bonds and other (2) — 2,406 47 2,453 Equity securities 1,859 370 21 2,250 Trading securities measured at net asset value (3) 111 Derivative financial instruments: Interest rate contracts 218 8,103 53 8,374 Foreign exchange contracts — 4,200 22 4,222 Equity-related contracts 39 73 33 145 Credit-related contracts — 143 1 144 Other contracts 15 12 20 47 Available-for-sale Japanese government bonds 15,771 678 — 16,449 Japanese local government bonds — 555 — 555 U.S. Treasury bonds and federal agency securities 376 — — 376 Other foreign government bonds 322 986 — 1,308 Agency mortgage-backed securities — 522 — 522 Residential mortgage-backed securities — 34 13 47 Commercial mortgage-backed securities — 862 — 862 Japanese corporate bonds and other debt securities — 2,008 101 2,109 Foreign corporate bonds and other debt securities — 916 90 1,006 Equity securities: Equity securities with readily determinable fair values 3,052 161 — 3,213 Equity securities measured at net asset value (3) 271 Other investments — — 63 63 Total assets measured at fair value on a recurring basis 25,414 30,162 464 56,422 Liabilities: Trading securities sold, not yet purchased 2,954 3,513 — 6,467 Derivative financial instruments: Interest rate contracts 244 8,271 2 8,517 Foreign exchange contracts — 4,005 8 4,013 Equity-related contracts 46 91 60 197 Credit-related contracts — 124 2 126 Other contracts 10 15 18 43 Long-term debt (4) — 1,844 836 2,680 Total liabilities measured at fair value on a recurring basis 3,254 17,863 926 22,043 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) The amount includes CLO and convertible bonds, which are classified in Level 3. (3) In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2022 and 2023 were ¥68 billion and ¥52 billion, respectively. (4) Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception.
Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following table presents a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the fiscal years ended March 31, 2022 and 2023: 2022 April 1, 2021 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2022 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 9 — (2) — — — — — — (1 ) 8 — Corporate bonds and other 1,033 7 (2) — — (452 ) 143 (72 ) — (588 ) 71 3 Equity securities 29 — (2) — — — — — — (1 ) 28 1 Derivative financial instruments, net (1) Interest rate contracts 8 11 (2) — — — — — — 3 22 (22 ) Foreign exchange contracts 23 8 (2) — — — — — — 1 32 7 Equity-related contracts (21 ) (11 ) (2) — — — — — — 18 (14 ) (23 ) Credit-related contracts 2 (3 ) (2) — — — — — — 2 1 (1 ) Other contracts — 1 (2) — — — — — — (1 ) — — Available-for-sale Residential mortgage-backed securities 23 — (3) — (4) — — — — — (5 ) 18 — Commercial mortgage-backed securities 716 5 (3) (5 ) (4) — (689 ) 62 (60 ) — (29 ) — — Japanese corporate bonds and other debt securities 365 (20 ) (3) 1 (4) — (4 ) 11 — — (38 ) 315 (19 ) Foreign corporate bonds and other debt securities 132 — (3) 7 (4) — (4 ) 47 — — (65 ) 117 1 Other investments 53 2 (3) — — — 37 (3 ) — (33 ) 56 (2 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — — — — — — — Long-term debt 713 61 (5) 1 (4) 4 (6 ) — — 534 (389 ) 794 77 2023 April 1, 2022 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2023 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 8 (1 ) (2) — — — — (6 ) — (1 ) — — Corporate bonds and other 71 4 (2) — 13 (15 ) 104 (46 ) — (84 ) 47 — Equity securities 28 — (2) — — — 2 (6 ) — (3 ) 21 (1 ) Derivative financial instruments, net (1) Interest rate contracts 22 31 (2) — — — — — — (2 ) 51 (22 ) Foreign exchange contracts 32 (5 ) (2) — — — — — — (13 ) 14 (6 ) Equity-related contracts (14 ) (26 ) (2) — — — — — — 13 (27 ) (107 ) Credit-related contracts 1 (1 ) (2) — — — — — — (1 ) (1 ) (5 ) Other contracts — 2 (2) — — — — — — — 2 2 Available-for-sale Residential mortgage-backed securities 18 — (3) — (4) — — — — — (5 ) 13 — Commercial mortgage-backed securities — — (3) — (4) — — — — — — — — Japanese corporate bonds and other debt securities 315 — (3) 3 (4) — — 25 — — (242 ) 101 8 Foreign corporate bonds and other debt securities 117 — (3) 1 (4) — (54 ) 63 — — (37 ) 90 — Other investments 56 3 (3) — — (1 ) 36 — — (31 ) 63 1 Liabilities: Trading securities sold, not yet purchased — — (2) — — — (1 ) 1 — — — — Long-term debt 794 29 (5) 10 (4) 1 (2 ) — — 323 (241 ) 836 60 Notes: (1) Total Level 3 derivative exposures have been netted on the table for presentation purposes only. (2) Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses). (3) Gains (losses) in Earnings are reported in Investment gains (losses)—net. (4) Gains (losses) in OCI are reported in Other comprehensive income (loss). (5) Gains (losses) in Earnings are reported in Other noninterest income (expenses). (6) Amounts represent total gains or losses recognized in earnings and other comprehensive income (loss) during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2022 and 2023. The amounts of unrealized gains (losses) in other comprehensive income (loss) are related to Available-for-sale securities and Long-term debt, which were ¥2 billion and ¥2 billion, respectively, at March 31, 2022, and ¥8 billion and ¥11 billion, respectively, at March 31, 2023.
Quantitative Information about Significant Unobservable Inputs Related to Material Classes of Level 3 Assets and Liabilities	The following table presents information about significant unobservable material liabilities at March 31, 2022 and 2023: 2022 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (4) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale securities: Residential mortgage-backed securities 26 Discounted cash flow Prepayment rate 0.4%–18.1% 5.8% Price-based Default rate 0.0%–0.5% 0.0% Recovery rate 100.0%–100.0% 100.0% Discount margin 30.0bps–167.1bps 53.1bps Corporate bonds and other debt securities 503 Discounted cash flow Prepayment rate (1) 5.8%–24.5% 24.3% Price-based Default rate (1) 0.2%–59.7% 0.7% Recovery rate (1) 10.0%–39.7% 39.5% Discount margin (1) 35.4bps–102.5bps 47.1bps Discount margin (2) 3.9bps–446.6bps 340.4bps Derivative financial instruments, net: Interest rate contracts 22 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% Foreign exchange contracts 32 Internal valuation model (3) FX – IR correlation 11.4%–52.3% 31.4% FX – FX correlation 41.4%–64.8% 53.1% Equity-related contracts (14 ) Internal valuation model (3) Equity – IR correlation 25.0%–25.0% 25.0% Equity correlation 3.2%–100.0% 89.9% Equity volatility 12.6%–120.5% 47.3% Credit-related contracts 1 Internal valuation model (3) Default rate 0.1%–8.0% 1.5% Credit correlation 42.6%–100.0% 66.2% Other contracts — Internal valuation model (3) Commodity volatility 0.0%–89.4% 55.4% Long-term debt 794 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% FX – IR correlation 11.4%–52.3% 38.9% FX – FX correlation 41.4%–64.8% 53.1% Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation -16.9%–16.8% 0.0% Equity correlation 3.2%–100.0% 89.6% Equity volatility 8.7%–120.5% 34.0% Default rate 0.1%–8.0% 1.5% Credit correlation 18.6%–100.0% 63.9% 2023 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (4) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 13 Discounted cash flow Prepayment rate 0.2%–17.6% 4.4% Price-based Default rate 0.0%–2.2% 0.2% Recovery rate 100.0%–100.0% 100.0% Discount margin 30.0bps–167.1bps 47.0bps Corporate bonds and other debt 238 Discounted cash flow Prepayment rate (1) 21.7%–21.7% 21.7% Price-based Default rate (1) 0.2%–0.2% 0.2% Recovery rate (1) 40.5%–40.5% 40.5% Discount margin (1) 98.8bps–209.9bps 116.2bps Discount margin (2) 3.5bps–171.2bps 20.1bps Derivative financial instruments, net: Interest rate contracts 51 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% Foreign exchange contracts 14 Internal valuation model (3) FX – IR correlation 5.5%–58.2% 39.9% FX – FX correlation 39.0%–64.7% 51.9% Equity-related contracts (27 ) Internal valuation model (3) Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation 0.0%–60.0% 33.7% Equity correlation 73.9%–100.0% 96.7% Equity volatility 10.3%–95.4% 44.1% Credit-related contracts (1 ) Internal valuation model (3) Default rate 0.1%–12.2% 2.1% Other contracts 2 Internal valuation model (3) Commodity volatility 20.0%–54.5% 39.8% Long-term debt 836 Internal valuation model (3) IR – IR correlation 23.2%–100.0% 75.0% FX – IR correlation 5.5%–58.2% 39.9% FX – FX correlation 39.0%–64.7% 51.9% Equity – IR correlation 25.0%–25.0% 25.0% Equity – FX correlation -16.3%–93.3% 0.0% Equity correlation 3.2%–100.0% 90.8% Equity volatility 5.9%–180.8% 34.1% Default rate 0.1%–13.1% 2.3% Credit correlation 47.6%–100.0% 68.3% Notes: (1) These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS. (2) This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds. (3) Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model. (4) Averages are calculated by weighting each input by the relative fair value of the respective financial instruments except for derivative related inputs where medians are used. (5) The range of inputs for equity securities is not disclosed, as there is a dispersion of values given the number of positions. IR = Interest rate FX = Foreign exchange
Summary of Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis	The following table shows the fair value hierarchy for these items as of March 31, 2022 and 2023: 2022 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 81 — — 81 128 Loans held-for-sale 76 — 27 49 77 Equity securities (without readily determinable fair values) 4 — 3 1 4 Premises and equipment—net — — — — 13 Other assets — — — — 3 Total assets measured at fair value on a nonrecurring basis 161 — 30 131 225 2023 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 97 — — 97 165 Loans held-for-sale 216 — 16 200 282 Equity securities (without readily determinable fair values) 4 — 4 — 5 Other investments 94 93 — 1 122 Premises and equipment—net 1 — — 1 2 Total assets measured at fair value on a nonrecurring basis 412 93 20 299 576 Note: The fair values may not be current as of the dates indicated, but rather as of the date the fair value change occurred. Accordingly, the carrying values may not equal current fair value.
Carrying Amounts and Fair Values of Certain Financial Instruments, Excluding Financial Instruments Carried at Fair Value on a Recurring Basis and Those outside Scope of ASC 825	The following table shows the carrying amounts and fair values at March 31, 2022 and 2023, of certain financial instruments, excluding financial instruments which are carried at fair value on a recurring basis and those outside the scope of ASC 825 such as equity method investments as defined in ASC 323, “Investments-Equity Method and Joint Ventures” (“ASC 323”) and lease contracts as defined in ASC 842, “Leases” (“ASC 842”): 2022 Carrying amount Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 68,366 68,366 50,628 17,738 — Investments 1,519 1,466 485 981 — Loans, net of allowance (Note) 89,264 90,576 — — 90,576 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 58,054 58,054 — 58,054 — Interest-bearing deposits 121,833 121,807 — 121,807 — Due to trust accounts 390 390 — 390 — Other short-term borrowings 7,567 7,567 — 7,567 — Long-term debt 9,849 9,681 — 8,162 1,519 2023 Carrying amount Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 83,226 83,226 66,498 16,728 — Investments 2,050 1,915 800 1,115 — Loans, net of allowance (Note) 93,291 94,605 — — 94,605 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 64,618 64,618 — 64,618 — Interest-bearing deposits 128,756 128,718 — 128,718 — Due to trust accounts 749 749 — 749 — Other short-term borrowings 3,397 3,397 — 3,397 — Long-term debt 12,246 11,719 — 10,315 1,404 Note: Loans, net of allowance include items measured at fair value on a nonrecurring basis.

Offsetting of financial asset_2

Offsetting of financial assets and financial liabilities (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Information of Offsetting of Financial Assets and Financial Liabilities	The following table provides information about the offsetting of financial assets and financial liabilities at March 31, 2022 and 2023. The table includes derivatives, repurchase and resale agreements, and securities lending and borrowing transactions that are subject to enforceable master netting arrangements or similar agreements irrespective of whether or not they are offset on the Group’s consolidated balance sheets. Amounts not offset on the balance sheet (3) Gross amounts recognized Gross amounts offset on the balance sheet Net amounts presented on the balance sheet (2) Financial instruments (4) Cash collateral Net amounts (in billions of yen) 2022 Assets (1) Derivatives 9,723 — 9,723 (5) (7,232 ) (891 ) 1,600 Receivables under resale agreements 12,751 — 12,751 (6) (11,437 ) — 1,314 Receivables under securities borrowing transactions 2,339 — 2,339 (7) (2,299 ) — 40 Total 24,813 — 24,813 (20,968 ) (891 ) 2,954 Liabilities (1) Derivatives 9,770 — 9,770 (5) (6,716 ) (1,329 ) 1,725 Payables under repurchase agreements 20,070 — 20,070 (6) (19,366 ) — 704 Payables under securities lending transactions 1,361 — 1,361 (7) (1,164 ) — 197 Total 31,201 — 31,201 (27,246 ) (1,329 ) 2,626 2023 Assets (1) Derivatives 12,932 — 12,932 (5) (10,476 ) (821 ) 1,635 Receivables under resale agreements 11,695 — 11,695 (6) (10,565 ) — 1,130 Receivables under securities borrowing transactions 1,892 — 1,892 (7) (1,866 ) — 26 Total 26,519 — 26,519 (22,907 ) (821 ) 2,791 Liabilities (1) Derivatives 12,896 — 12,896 (5) (10,141 ) (843 ) 1,912 Payables under repurchase agreements 25,737 — 25,737 (6) (25,113 ) — 624 Payables under securities lending transactions 886 — 886 (7) (755 ) — 131 Total 39,519 — 39,519 (36,009 ) (843 ) 2,667 Notes: (1) Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off over-the-counter OTC-cleared (2) Derivative assets and liabilities are recorded in Trading account assets and Trading account liabilities, respectively. (3) Amounts do not exceed the net amounts presented on the balance sheet and do not include the effect of overcollateralization, where it exists. (4) For derivatives, amounts include derivative assets or liabilities and securities collateral that are eligible for offsetting under enforceable master netting arrangements or similar agreements. (5) The amounts of derivative assets and liabilities subject to enforceable master netting arrangements or similar agreements were ¥9,326 billion and ¥9,235 billion, respectively, at March 31, 2022, and ¥12,574 billion and ¥12,432 billion, respectively, at March 31, 2023. (6) The amounts of Receivables under resale agreements and Payables under repurchase agreements subject to enforceable industry standard master repurchase agreements with netting terms were ¥11,537 billion and ¥19,505 billion, respectively, at March 31, 2022, and ¥10,587 billion and ¥25,147 billion , (7) The amounts of Receivables under securities borrowing transactions and Payables under securities lending transactions subject to enforceable industry standard master lending agreements with netting terms were ¥2,339 billion and ¥1,172 billion, respectively, at March 31, 2022, and ¥1,892 billion and ¥758 billion ,

Repurchase agreements and sec_2

Repurchase agreements and securities lending transactions accounted for as secured borrowings (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Gross Amounts of Liabilities by Remaining Contractual Maturity	The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by remaining contractual maturity at March 31, 2022 and 2023: Overnight and continuous Up to 30 days 31-90 days Greater than 90 days Total (in billions of yen) 2022 Repurchase agreements 7,011 10,621 1,340 1,098 20,070 Securities lending transactions 1,098 74 — 189 1,361 Total 8,109 10,695 1,340 1,287 21,431 2023 Repurchase agreements 2,285 16,508 5,471 1,473 25,737 Securities lending transactions 685 73 — 128 886 Total 2,970 16,581 5,471 1,601 26,623
Gross Amounts of Liabilities by Class of Underlying Collateral	The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by class of underlying collateral at March 31, 2022 and 2023: Repurchase agreements Securities lending transactions (in billions of yen) 2022 Japanese government bonds and Japanese local government bonds 1,714 217 Foreign government bonds and foreign agency mortgage-backed securities 17,445 90 Commercial paper and corporate bonds 271 52 Equity securities 609 989 Other 31 13 Total 20,070 1,361 2023 Japanese government bonds and Japanese local government bonds 6,114 102 Foreign government bonds and foreign agency mortgage-backed securities 17,475 73 Commercial paper and corporate bonds 430 — Equity securities 1,491 711 Other 227 — Total 25,737 886

Related Party Transactions (Tab

Related Party Transactions (Table)	12 Months Ended
	Mar. 31, 2023
Related Party Transactions [Abstract]
Summary of financial information of groups equity method investees	Summarized financial information of the MHFG Group’s equity method investees as of March 31, 2022 and 2023, and for each of the three years ended March 31, 2023, is as follows: 2022 2023 (in billions of yen) Loans 7,765 6,037 Total assets 30,180 29,367 Deposits 8,713 6,216 Total liabilities 27,474 26,506 Total equity 2,706 2,861 Noncontrolling interests 14 16 2021 2022 2023 (in billions of yen) Total interest and dividend income 570 625 750 Total interest expense 188 182 239 Provision (credit) for credit losses 91 104 96 Net interest income after provision (credit) for credit losses 291 339 415 Income before income tax expense 237 332 261 Net income 178 246 194

Business segment information (T

Business segment information (Tables)	12 Months Ended
	Mar. 31, 2023
Statement [Line Items]
Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP	The reportable segment information, set forth below, is derived from the internal management reporting systems used by management to measure the performance of the Group’s operating segments. Management measures the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. In addition, the format and information are presented primarily on the basis of Japanese GAAP. Therefore, they are not consistent with the consolidated financial statements prepared in accordance with U.S. GAAP. A reconciliation is provided for the total amount of all business segments’ “Net business profits (losses) + Net gains (losses) related to ETFs and others” with income before income tax expense under U.S. GAAP, and the total amount of all business segments’ “Fixed assets” with the total amount of Premises and equipment-net, right-of-use The MHFG Group partially restructured in-house segments. MHFG (Consolidated) 2021 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 699.4 475.5 519.0 495.9 50.8 (39.8 ) 2,200.8 General and administrative expenses (3) 642.5 209.8 292.4 224.3 33.0 6.7 1,408.7 Equity in earnings (losses) of equity method investees—net 5.4 3.9 13.2 — 1.2 (3.8 ) 19.9 Amortization of goodwill and others 2.3 0.1 0.4 0.8 7.6 1.0 12.2 Net business profits (losses) (4) 60.0 269.5 239.4 270.8 11.4 (51.3 ) 799.8 Fixed assets (5) 532.8 192.5 169.5 98.1 — 762.8 1,755.7 MHFG (Consolidated) 2022 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 715.0 494.4 592.8 388.1 59.5 4.7 2,254.5 General and administrative expenses (3) 623.7 201.4 300.0 234.7 33.4 21.8 1,415.0 Equity in earnings (losses) of equity method investees—net 5.9 3.8 16.0 — 1.5 (1.8 ) 25.4 Amortization of goodwill and others 2.2 0.1 0.4 0.8 7.2 1.0 11.7 Net business profits (losses) (4) 95.0 296.7 308.4 152.6 20.4 (19.9 ) 853.2 Fixed assets (5) 493.0 159.1 161.8 88.5 — 794.9 1,697.3 MHFG (Consolidated) 2023 (1) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (6) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (2) 704.0 502.3 672.2 321.2 55.2 25.3 2,280.2 General and administrative expenses (3) 611.6 197.3 323.0 258.0 35.2 48.5 1,473.6 Equity in earnings (losses) of equity method investees—net (17.0 ) 6.4 22.8 — 0.2 (0.5 ) 11.9 Amortization of goodwill and others 2.1 0.1 0.7 0.8 6.8 0.9 11.4 Net business profits (losses) (4) 73.3 311.3 371.3 62.4 13.4 (24.6 ) 807.1 Fixed assets (5) 489.3 150.1 173.7 87.9 — 777.6 1,678.6 Notes: (1) Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates. (2) “Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated (3) “General and administrative expenses” excludes non-allocated (4) Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses (excluding non-allocated amortization of goodwill and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan. (5) “Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net; right-of-use (6) “Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including elimination of internal transaction between each segment; • equity in earnings (losses) of equity method investees—net that are not subject to allocation; and • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value.
Reconciliation of Total Net Business Profits under Internal Management Reporting Systems to Income Before Income Tax Expense on Consolidated Statements of Income	A reconciliation of “Net business profits (losses) + Net gains (losses) related to ETFs and others” for the fiscal years ended March 31, 2021, 2022 and 2023 presented above to income (loss) before income tax expense (benefit) shown on the consolidated statements of income and a reconciliation of “Fixed assets” at March 31, 2022 and 2023 to the total amount of Premises and equipment-net, right-of-use 2021 2022 2023 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 799.8 853.2 807.1 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated 6.3 33.7 39.7 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (209.9 ) (255.9 ) (96.7 ) Gains on reversal of reserves for possible losses on loans, and others 4.9 20.8 7.4 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others 10.1 (45.8 ) 84.6 Net extraordinary gains (losses) 115.9 44.0 (10.6 ) Others (74.9 ) (46.1 ) (52.5 ) Income before income tax expense under Japanese GAAP 652.2 603.9 779.0 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (86.4 ) (124.0 ) (373.2 ) Investments 523.5 (600.1 ) (210.5 ) Loans (16.9 ) (18.3 ) (30.3 ) Allowances for credit losses 83.3 51.5 (9.8 ) Premises and equipment (56.5 ) (68.5 ) (29.3 ) Land revaluation 6.4 6.4 5.6 Business combinations (1.0 ) 6.9 8.9 Pension liabilities (153.2 ) (94.4 ) (71.6 ) Consolidation of variable interest entities 104.6 42.3 0.8 Foreign currency translation (31.5 ) (51.0 ) (5.2 ) Others 4.3 2.8 4.8 Income (loss) before income tax expense (benefit) under U.S. GAAP 1,028.8 (242.5 ) 69.2
Reconciliation of Assets from Segment to Consolidated	2021 2022 2023 (in billions of yen) Fixed assets 1,755.7 1,697.3 1,678.6 U.S. GAAP adjustments (Note) 816.1 717.6 662.6 Premises and equipment-net, right-of-use 2,571.8 2,414.9 2,341.2 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from right-of-use

Foreign activities (Tables)

Foreign activities (Tables)	12 Months Ended
	Mar. 31, 2023
Text Block [Abstract]
Consolidated Income Statement and Total Assets Information by Major Geographic Area	The following table presents consolidated income statement and total assets information by major geographic area. Foreign activities are defined as business transactions that involve customers residing outside of Japan. However, as the MHFG Group’s operations are highly integrated globally, estimates and assumptions have been made for an allocation among the geographic areas. Americas Japan United States of America Others Europe Asia/Oceania excluding Japan, and others Total (in billions of yen) Fiscal year ended March 31, 2021: Total revenue (1) 2,290.8 503.8 154.5 188.7 360.1 3,497.9 Total expenses (2) 1,918.2 243.5 14.4 115.8 177.2 2,469.1 Income before income tax expense 372.6 260.3 140.1 72.9 182.9 1,028.8 Net income 235.6 227.4 137.2 60.9 156.9 818.0 Total assets at end of fiscal year 152,613.7 31,939.9 4,405.3 14,150.6 18,542.0 221,651.5 Fiscal year ended March 31, 2022: Total revenue (1) 991.1 562.9 41.7 184.8 333.2 2,113.7 Total expenses (2) 1,713.8 265.0 19.0 189.2 169.2 2,356.2 Income (loss) before income tax expense (benefit) (722.7 ) 297.9 22.7 (4.4 ) 164.0 (242.5 ) Net income (loss) (509.0 ) 275.2 18.3 (16.3 ) 130.3 (101.5 ) Total assets at end of fiscal year 155,111.2 36,765.7 3,667.9 15,795.9 20,210.0 231,550.7 Fiscal year ended March 31, 2023: Total revenue (1) 1,104.7 1,841.5 93.1 445.9 791.7 4,276.9 Total expenses (2) 1,784.1 1,455.4 84.7 413.0 470.5 4,207.7 Income (loss) before income tax expense (benefit) (679.4 ) 386.1 8.4 32.9 321.2 69.2 Net income (loss) (554.7 ) 297.2 1.8 19.9 269.8 34.0 Total assets at end of fiscal year 161,348.7 45,516.4 3,579.6 16,634.7 21,701.3 248,780.7 Notes: (1) Total revenue is comprised of Interest and dividend income and Noninterest income. (2) Total expenses are comprised of Interest expense, Provision (credit) for credit losses and Noninterest expenses.

Mizuho Financial Group, Inc.,_2

Mizuho Financial Group, Inc., parent company (Tables)	12 Months Ended
	Mar. 31, 2023
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheets	Condensed balance sheets 2022 2023 (in millions of yen) Assets: Cash and due from banking subsidiaries 51,356 47,425 Interest-bearing deposits in banking subsidiaries 414 450 Investments in subsidiaries and affiliated companies: Banking subsidiaries 8,102,149 7,996,767 Non-banking 878,776 1,075,322 Long-term loans receivable from subsidiaries: A banking subsidiary 7,942,367 8,768,725 A non-banking 399,000 444,000 Other assets 648,946 545,744 Total 18,023,008 18,878,433 Liabilities and shareholders’ equity: Short-term borrowings from a banking subsidiary 755,000 810,000 Long-term debt 7,957,710 8,741,729 Other liabilities 396,086 411,213 Shareholders’ equity 8,914,212 8,915,491 Total 18,023,008 18,878,433
Condensed Statements of Income	Condensed statements of income 2021 2022 2023 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 214,473 197,717 209,257 Non-banking 17,499 82,105 62,698 Management fees from subsidiaries 36,334 40,462 43,900 Interest income on loans and discounts 128,697 133,215 177,137 Gains on sales of investments in subsidiaries 40 53,005 — Other income 11,970 11,319 37,319 Total 409,013 517,823 530,311 Expenses: Operating expenses 37,979 43,192 52,887 Interest expense 130,812 130,453 175,723 Losses on sales of investments in a subsidiary — 26,606 — Other expense 8,842 5,946 2,768 Total 177,633 206,197 231,378 Equity in undistributed net income (loss) of subsidiaries and affiliated companies—net 341,369 (505,891 ) (307,879 ) Income (loss) before income tax expense (benefit) 572,749 (194,265 ) (8,946 ) Income tax expense (benefit) (9,016 ) (89,543 ) 5,063 Net income (loss) 581,765 (104,722 ) (14,009 )
Condensed Statements of Cash Flows	Condensed statements of cash flows 2021 2022 2023 (in millions of yen) Cash flows from operating activities: Net income (loss) 581,765 (104,722 ) (14,009 ) Adjustments and other (390,748 ) 351,484 394,191 Net cash provided by operating activities 191,017 246,762 380,182 Cash flows from investing activities: Net change in loans (1,167,385 ) (72,313 ) (511,934 ) Purchases of premises and equipment (41,382 ) (26 ) (81 ) Proceeds from sales of premises and equipment 55,624 11 — Purchases of investments in a subsidiary — — (179,210 ) Proceeds from sales of investments in subsidiaries 125 452,500 721 Net change in other investing activities (1,370 ) 223 (5,591 ) Net cash provided by (used in) investing activities (1,154,388 ) 380,395 (696,095 ) Cash flows from financing activities: Net change in short-term borrowings (10,000 ) (95,000 ) 55,000 Proceeds from issuance of long-term debt 1,477,385 930,033 1,497,032 Repayment of long-term debt (310,000 ) (1,256,720 ) (1,030,099 ) Purchases of treasury stock (1,849 ) (1,927 ) (1,575 ) Dividends paid (190,498 ) (196,783 ) (209,457 ) Net change in other financing activities 65 44 1,117 Net cash provided by (used in) financing activities 965,103 (620,353 ) 312,018 Net increase (decrease) in cash and cash equivalents 1,732 6,804 (3,895 ) Cash and cash equivalents at beginning of fiscal year 43,234 44,966 51,770 Cash and cash equivalents at end of fiscal year 44,966 51,770 47,875

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2023 ¥ / shares shares
Stock Acquisition Rights [Member]
Disclosure of Accounting Policies [Line Items]
Number of shares | shares	100
Exercise price | ¥ / shares	¥ 1
Contractual term	20 years
Minimum
Disclosure of Accounting Policies [Line Items]
Period in which obligors generally determined to be substantially bankrupt, past due (in months)	6 months
Minimum | Software and Software Development Costs
Disclosure of Accounting Policies [Line Items]
Estimated useful life	5 years
Maximum | Software and Software Development Costs
Disclosure of Accounting Policies [Line Items]
Estimated useful life	10 years
Impaired loans | Minimum
Disclosure of Accounting Policies [Line Items]
Number of days past due	90 days
Customer Relationships [Member] | Shinko Securities Company Limited
Disclosure of Accounting Policies [Line Items]
Weighted-average amortization period	16 years
Customer Relationships [Member] | Asset Management Company
Disclosure of Accounting Policies [Line Items]
Weighted-average amortization period	16 years 10 months 24 days

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies (Useful Lives of Premises and Equipment) (Detail)	12 Months Ended
	Mar. 31, 2023
Minimum | Buildings
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	3 years
Minimum | Equipment and furniture
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	2 years
Maximum | Buildings
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	50 years
Maximum | Equipment and furniture
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	20 years

Investments - Amortized Cost, G

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		¥ 71,417	¥ 58,803
Fair value, available-for-sale securities		23,233,769	31,673,890
Amortized cost, held-to-maturity securities		2,050,107	1,519,055
Total		1,915,108
Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		37,496	38,379
Debt securities | Japanese local government bonds
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		5,628	2,165
Debt securities | U.S. Treasury bonds and federal agency securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		7,289	8,444
Debt securities | Other foreign government bonds
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		2,261	2,578
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities	[1]	11,307	3,985
Debt securities | Residential mortgage-backed securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		866	312
Debt securities | Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		451	214
Debt securities | Japanese corporate bonds and other debt securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		4,538	1,705
Debt securities | Foreign corporate bonds and other debt securities
Schedule of Investments [Line Items]
Gross unrealized losses, available-for-sale securities		1,581	1,021
Available-for-sale securities | Debt securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	23,279,549	31,702,397
Gross unrealized gains, available-for-sale securities		25,637	30,296
Gross unrealized losses, available-for-sale securities		71,417	58,803
Fair value, available-for-sale securities		23,233,769	31,673,890
Available-for-sale securities | Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	16,483,722	25,191,315
Gross unrealized gains, available-for-sale securities		3,067	5,794
Gross unrealized losses, available-for-sale securities		37,496	38,379
Fair value, available-for-sale securities		16,449,293	25,158,730
Available-for-sale securities | Debt securities | Japanese local government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	560,093	421,557
Gross unrealized gains, available-for-sale securities		198	254
Gross unrealized losses, available-for-sale securities		5,628	2,165
Fair value, available-for-sale securities		554,663	419,646
Available-for-sale securities | Debt securities | U.S. Treasury bonds and federal agency securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	382,990	381,653
Gross unrealized gains, available-for-sale securities		0	0
Gross unrealized losses, available-for-sale securities		7,289	8,444
Fair value, available-for-sale securities		375,701	373,209
Available-for-sale securities | Debt securities | Other foreign government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	1,309,473	1,338,295
Gross unrealized gains, available-for-sale securities		661	220
Gross unrealized losses, available-for-sale securities		2,261	2,578
Fair value, available-for-sale securities		1,307,873	1,335,937
Available-for-sale securities | Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3],[4]	532,364	452,830
Gross unrealized gains, available-for-sale securities	[4]	1,140	1,695
Gross unrealized losses, available-for-sale securities	[4]	11,307	3,985
Fair value, available-for-sale securities	[4]	522,197	450,540
Available-for-sale securities | Debt securities | Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	48,257	58,246
Gross unrealized gains, available-for-sale securities		71	194
Gross unrealized losses, available-for-sale securities		866	312
Fair value, available-for-sale securities		47,462	58,128
Available-for-sale securities | Debt securities | Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	856,708	848,568
Gross unrealized gains, available-for-sale securities		5,157	5,437
Gross unrealized losses, available-for-sale securities		451	214
Fair value, available-for-sale securities		861,414	853,791
Available-for-sale securities | Debt securities | Japanese corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3]	2,100,733	2,222,670
Gross unrealized gains, available-for-sale securities		13,024	14,212
Gross unrealized losses, available-for-sale securities		4,538	1,705
Fair value, available-for-sale securities		2,109,219	2,235,177
Available-for-sale securities | Debt securities | Foreign corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[2],[3],[5]	1,005,209	787,263
Gross unrealized gains, available-for-sale securities	[5]	2,319	2,490
Gross unrealized losses, available-for-sale securities	[5]	1,581	1,021
Fair value, available-for-sale securities	[5]	1,005,947	788,732
Held-to-maturity Securities | Debt securities
Schedule of Investments [Line Items]
Amortized cost, held-to-maturity securities	[2],[3]	2,050,107	1,519,055
Gross unrealized gains, held-to-maturity securities		2,574	5,125
Gross unrealized losses, held-to-maturity securities		137,573	58,604
Total		1,915,108	1,465,576
Held-to-maturity Securities | Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Amortized cost, held-to-maturity securities	[2],[3]	799,305	479,980
Gross unrealized gains, held-to-maturity securities		2,171	5,101
Gross unrealized losses, held-to-maturity securities		1,028	0
Total		800,448	485,081
Held-to-maturity Securities | Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, held-to-maturity securities	[2],[3],[6]	1,250,802	1,039,075
Gross unrealized gains, held-to-maturity securities	[6]	403	24
Gross unrealized losses, held-to-maturity securities	[6]	136,545	58,604
Total	[6]	¥ 1,114,660	¥ 980,495
[1]Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥261,867 million at March 31, 2022, and ¥381,634 million at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.[2]Accrued interest receivables are excluded from amortized cost, of which the amount were ¥4,702 million at March 31, 2022, and ¥5,637 million at March 31, 2023 and included in Accrued income.[3]Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale securities were ¥34,326 million at March 31, 2022, and ¥nil at March 31, 2023.[4]Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥450,507 million and ¥33 million, respectively, at March 31, 2022, and ¥522,166 million and ¥31 million, respectively, at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government.[5]Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥247,762 million at March 31, 2022, and ¥330,365 million at March 31, 2023.[6]All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.

Investments - Amortized Cost,_2

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	¥ 23,233,769	¥ 31,673,890
Accrued income
Schedule of Investments [Line Items]
Accrued interest receivables	198,000	81,000
Net of Allowance for Credit Loss [Member]
Schedule of Investments [Line Items]
Amortised cost net of allowance for credit loss available for sale securities	0	34,326
Debt securities | Negotiable certificates of deposits, asset- backed securities and collateral loan obligations
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	330,365	247,762
Debt securities | Japanese agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	522,166	450,507
Debt securities | Foreign agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	31	33
Available-for sale and held-to-maturity securities | Accrued income
Schedule of Investments [Line Items]
Accrued interest receivables	¥ 5,637	¥ 4,702

Investments - Amortized Cost an

Investments - Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	¥ 16,693,211
Due after one year through five years, amortized cost	3,312,191
Due after five years through ten years, amortized cost	2,271,914
Due after ten years, amortized cost	1,002,233
Total	23,279,549
Due in one year or less, amortized cost	279,982
Due after one year through five years, amortized cost	189,984
Due after five years through ten years, amortized cost	329,339
Due after ten years, amortized cost	1,250,802
Amortized cost, held-to-maturity securities	2,050,107	¥ 1,519,055
Due in one year or less, fair value	16,686,719
Due after one year through five years, fair value	3,310,463
Due after five years through ten years, fair value	2,240,655
Due after ten years, fair value	995,932
Total	23,233,769
Due in one year or less, fair value	280,980
Due after one year through five years, fair value	190,917
Due after five years through ten years, fair value	328,551
Due after ten years, fair value	1,114,660
Total	1,915,108
Debt securities | Japanese government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	14,280,736
Due after one year through five years, amortized cost	783,953
Due after five years through ten years, amortized cost	1,317,250
Due after ten years, amortized cost	101,783
Total	16,483,722
Due in one year or less, amortized cost	279,982
Due after one year through five years, amortized cost	189,984
Due after five years through ten years, amortized cost	329,339
Due after ten years, amortized cost	0
Amortized cost, held-to-maturity securities	799,305
Due in one year or less, fair value	14,282,254
Due after one year through five years, fair value	782,278
Due after five years through ten years, fair value	1,290,250
Due after ten years, fair value	94,511
Total	16,449,293
Due in one year or less, fair value	280,980
Due after one year through five years, fair value	190,917
Due after five years through ten years, fair value	328,551
Due after ten years, fair value	0
Total	800,448
Debt securities | Japanese local government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	35,545
Due after one year through five years, amortized cost	275,695
Due after five years through ten years, amortized cost	241,350
Due after ten years, amortized cost	7,503
Total	560,093
Due in one year or less, fair value	35,551
Due after one year through five years, fair value	275,371
Due after five years through ten years, fair value	236,653
Due after ten years, fair value	7,088
Total	554,663
Debt securities | U.S. Treasury bonds and federal agency securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	382,990
Due after one year through five years, amortized cost	0
Due after five years through ten years, amortized cost	0
Due after ten years, amortized cost	0
Total	382,990
Due in one year or less, fair value	375,701
Due after one year through five years, fair value	0
Due after five years through ten years, fair value	0
Due after ten years, fair value	0
Total	375,701
Debt securities | Other foreign government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	1,027,119
Due after one year through five years, amortized cost	279,985
Due after five years through ten years, amortized cost	1,186
Due after ten years, amortized cost	1,183
Total	1,309,473
Due in one year or less, fair value	1,026,121
Due after one year through five years, fair value	279,384
Due after five years through ten years, fair value	1,186
Due after ten years, fair value	1,182
Total	1,307,873
Debt securities | Agency mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	0
Due after one year through five years, amortized cost	0
Due after five years through ten years, amortized cost	1,118
Due after ten years, amortized cost	531,246
Total	532,364
Due in one year or less, amortized cost	0
Due after one year through five years, amortized cost	0
Due after five years through ten years, amortized cost	0
Due after ten years, amortized cost	1,250,802
Amortized cost, held-to-maturity securities	1,250,802
Due in one year or less, fair value	0
Due after one year through five years, fair value	0
Due after five years through ten years, fair value	1,113
Due after ten years, fair value	521,084
Total	522,197
Due in one year or less, fair value	0
Due after one year through five years, fair value	0
Due after five years through ten years, fair value	0
Due after ten years, fair value	1,114,660
Total	1,114,660
Debt securities | Residential mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	0
Due after one year through five years, amortized cost	0
Due after five years through ten years, amortized cost	0
Due after ten years, amortized cost	48,257
Total	48,257
Due in one year or less, fair value	0
Due after one year through five years, fair value	0
Due after five years through ten years, fair value	0
Due after ten years, fair value	47,462
Total	47,462
Debt securities | Commercial mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	1,986
Due after one year through five years, amortized cost	538,136
Due after five years through ten years, amortized cost	315,886
Due after ten years, amortized cost	700
Total	856,708
Due in one year or less, fair value	1,989
Due after one year through five years, fair value	540,069
Due after five years through ten years, fair value	318,645
Due after ten years, fair value	711
Total	861,414
Debt securities | Japanese corporate bonds and other debt securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	412,207
Due after one year through five years, amortized cost	1,155,415
Due after five years through ten years, amortized cost	240,446
Due after ten years, amortized cost	292,665
Total	2,100,733
Due in one year or less, fair value	412,157
Due after one year through five years, fair value	1,154,386
Due after five years through ten years, fair value	238,775
Due after ten years, fair value	303,901
Total	2,109,219
Debt securities | Foreign corporate bonds and other debt securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost	552,628
Due after one year through five years, amortized cost	279,007
Due after five years through ten years, amortized cost	154,678
Due after ten years, amortized cost	18,896
Total	1,005,209
Due in one year or less, fair value	552,946
Due after one year through five years, fair value	278,975
Due after five years through ten years, fair value	154,033
Due after ten years, fair value	19,993
Total	¥ 1,005,947

Investments - Additional Inform

Investments - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 598,772	¥ 519,552
Japanese corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Credit losses on available-for-sale securities	0		¥ 14,000
Debt securities, available-for-sale, allowance for credit loss, period increase (decrease)	(34,000)	34,000	20,000
Held-to-maturity Securities | Japanese government bonds
Gain (Loss) on Securities [Line Items]
Credit losses on available-for-sale securities	¥ 0	0	¥ 0
Orient Corporation
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	49%
Joint Stock Commercial Bank Foreign Trade of Vietnam [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	15%
Mizuho Leasing Company LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	23.54%
Matthew International Capital Management LLC [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	18.73%
Custody Bank of Japan Ltd [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	27%
Rakuten Securities, Inc [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	20%
Equity securities (marketable)
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 268,736	255,336
Equity method Investments, aggregated market values	¥ 503,171	¥ 456,195

Investments - Gross Unrealized

Investments - Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		¥ 6,269,815	¥ 21,846,469
Less than 12 months Gross unrealized losses, available-for-sale securities		22,388	26,771
12 months or more Fair value, available-for-sale securities		3,293,501	2,032,092
12 months or more Gross unrealized losses, available-for-sale securities		49,029	32,032
Total Fair value, available-for-sale securities		9,563,316	23,878,561
Total Gross unrealized losses, available-for-sale securities		71,417	58,803
Debt securities | Japanese government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		3,706,134	19,407,878
Less than 12 months Gross unrealized losses, available-for-sale securities		11,369	11,377
12 months or more Fair value, available-for-sale securities		1,419,222	1,565,950
12 months or more Gross unrealized losses, available-for-sale securities		26,127	27,002
Total Fair value, available-for-sale securities		5,125,356	20,973,828
Total Gross unrealized losses, available-for-sale securities		37,496	38,379
Debt securities | Japanese local government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		146,484	229,562
Less than 12 months Gross unrealized losses, available-for-sale securities		1,596	1,277
12 months or more Fair value, available-for-sale securities		322,224	136,733
12 months or more Gross unrealized losses, available-for-sale securities		4,032	888
Total Fair value, available-for-sale securities		468,708	366,295
Total Gross unrealized losses, available-for-sale securities		5,628	2,165
Debt securities | U.S. Treasury bonds and federal agency securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		65,288	321,073
Less than 12 months Gross unrealized losses, available-for-sale securities		765	7,209
12 months or more Fair value, available-for-sale securities		293,149	41,555
12 months or more Gross unrealized losses, available-for-sale securities		6,524	1,235
Total Fair value, available-for-sale securities		358,437	362,628
Total Gross unrealized losses, available-for-sale securities		7,289	8,444
Debt securities | Other foreign government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		475,493	729,134
Less than 12 months Gross unrealized losses, available-for-sale securities		674	2,178
12 months or more Fair value, available-for-sale securities		250,130	71,647
12 months or more Gross unrealized losses, available-for-sale securities		1,587	400
Total Fair value, available-for-sale securities		725,623	800,781
Total Gross unrealized losses, available-for-sale securities		2,261	2,578
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities	[1]	142,776	183,150
Less than 12 months Gross unrealized losses, available-for-sale securities	[1]	2,361	2,326
12 months or more Fair value, available-for-sale securities	[1]	238,858	78,717
12 months or more Gross unrealized losses, available-for-sale securities	[1]	8,946	1,659
Total Fair value, available-for-sale securities	[1]	381,634	261,867
Total Gross unrealized losses, available-for-sale securities	[1]	11,307	3,985
Debt securities | Residential mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		16,230	9,221
Less than 12 months Gross unrealized losses, available-for-sale securities		265	11
12 months or more Fair value, available-for-sale securities		22,017	17,193
12 months or more Gross unrealized losses, available-for-sale securities		601	301
Total Fair value, available-for-sale securities		38,247	26,414
Total Gross unrealized losses, available-for-sale securities		866	312
Debt securities | Commercial mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		105,346	58,815
Less than 12 months Gross unrealized losses, available-for-sale securities		304	185
12 months or more Fair value, available-for-sale securities		43,653	13,939
12 months or more Gross unrealized losses, available-for-sale securities		147	29
Total Fair value, available-for-sale securities		148,999	72,754
Total Gross unrealized losses, available-for-sale securities		451	214
Debt securities | Japanese corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		1,177,725	605,067
Less than 12 months Gross unrealized losses, available-for-sale securities		3,775	1,516
12 months or more Fair value, available-for-sale securities		635,289	53,020
12 months or more Gross unrealized losses, available-for-sale securities		763	189
Total Fair value, available-for-sale securities		1,813,014	658,087
Total Gross unrealized losses, available-for-sale securities		4,538	1,705
Debt securities | Foreign corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		434,339	302,569
Less than 12 months Gross unrealized losses, available-for-sale securities		1,279	692
12 months or more Fair value, available-for-sale securities		68,959	53,338
12 months or more Gross unrealized losses, available-for-sale securities		302	329
Total Fair value, available-for-sale securities		503,298	355,907
Total Gross unrealized losses, available-for-sale securities		¥ 1,581	¥ 1,021
[1]Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥261,867 million at March 31, 2022, and ¥381,634 million at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.

Investments - Gross Unrealize_2

Investments - Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 9,563,316	¥ 23,878,561
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities	[1]	381,634	261,867
Debt securities | Japanese agency mortgage-backed securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 381,634	¥ 261,867
[1]Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥261,867 million at March 31, 2022, and ¥381,634 million at March 31, 2023. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.

Investments - Realized Gains an

Investments - Realized Gains and Losses on Sales of Available-for-Sale Securities (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Gross realized gains	¥ 22,962	¥ 12,540	¥ 3,309
Gross realized losses	(23,593)	(40,077)	(24,407)
Net realized gains (losses) on sales of available-for-sale securities	¥ (631)	¥ (27,537)	¥ (21,098)

Investments - Summary of Detail

Investments - Summary of Details of Net Gains and Losses on Equity Securities (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Gain (Loss) on Securities [Line Items]
Net gains (losses) recognized during the period on equity securities	¥ 135,601	¥ (60,563)	¥ 850,567
Less: Net gains (losses) recognized during the period on equity securities sold during the period	29,561	17,000	82,969
Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period	¥ 106,040	¥ (77,563)	¥ 767,598

Investments - Summary of Equity

Investments - Summary of Equity Securities Without Readily Determinable Fair Values (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Equity Securities without Readily Determinable Fair Value [Line Items]
Carrying amounts at the end of the period	¥ 207,743	¥ 207,407	¥ 186,146
Downward adjustments and impairments	5,345	6,519	5,087
Upward adjustments	¥ 13,015	¥ 11,623	¥ 9,216

Investments - Summary of Downwa

Investments - Summary of Downward Adjustments and Impairments and Upward Adjustments (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Equity Securities without Readily Determinable Fair Value [Line Items]
Downward adjustments and impairments	¥ 1,291	¥ 2,626	¥ 3,084
Upward adjustments	¥ 1,459	¥ 2,459	¥ 404

Investments - Summary of Compos

Investments - Summary of Composition of Other Investments (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Schedule of Investments [Line Items]
Equity method investments	¥ 598,772	¥ 519,552
Investments held by consolidated investment companies and other	68,429	62,836
Total	¥ 667,201	¥ 582,388

Loans - Additional Information

Loans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net losses on sales of loans	¥ 13,436	¥ 3,080	¥ 8,172
Unearned Income And Deferred Loan Fees	¥ 238,000	¥ 196,000
Accounts Receivable, Noncurrent, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued Investment Income Receivable	Accrued Investment Income Receivable
Accrued income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivables	¥ 198,000	¥ 81,000
Impaired Financing Receivables with No Related Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans partially charged off	¥ 11,314	¥ 13,046

Loans - Credit Quality Informat

Loans - Credit Quality Information of Loans Based on MHFG Group's Internal Rating System (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Normal obligors | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	¥ 711	¥ 798
2020	570	544
2019	476	519
2018	468	527
2017	478	544
Prior to 2017	4,723	4,753
Revolving loan	0	0
Total	7,426	7,685
Normal obligors | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	184	196
2020	87	277
2019	226	112
2018	80	91
2017	64	61
Prior to 2017	297	315
Revolving loan	484	497
Total	1,422	1,549
Watch obligors | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	1	2
2020	2	1
2019	1	2
2018	2	2
2017	1	1
Prior to 2017	35	40
Revolving loan	0	0
Total	42	48
Watch obligors | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	22	24
2020	6	35
2019	21	10
2018	5	8
2017	4	4
Prior to 2017	5	6
Revolving loan	8	9
Total	71	96
Non Accrual Loans | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	8	12
2020	2	3
2019	2	1
2018	1	1
2017	1	1
Prior to 2017	25	31
Revolving loan	0	0
Total	39	49
Non Accrual Loans | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	9	7
2020	4	8
2019	6	3
2018	2	4
2017	4	4
Prior to 2017	20	23
Revolving loan	10	13
Total	55	62
Financing Receivables Not Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	32,710	30,802
2020	11,611	12,277
2019	9,195	10,121
2018	7,416	7,631
2017	5,355	3,495
Prior to 2017	11,438	11,020
Revolving loan	16,451	14,945
Total	94,176	90,291
Financing Receivables Not Impaired | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	15,428	15,072
2020	7,142	8,261
2019	6,667	6,611
2018	5,242	5,925
2017	4,252	2,715
Prior to 2017	10,035	9,736
Revolving loan	9,164	8,712
Total	57,930	57,032
Financing Receivables Not Impaired | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	17,282	15,730
2020	4,469	4,016
2019	2,528	3,510
2018	2,174	1,706
2017	1,103	780
Prior to 2017	1,403	1,284
Revolving loan	7,287	6,233
Total	36,246	33,259
Financing Receivables Not Impaired | Normal obligors | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	1,217	938
2020	54	106
2019	90	89
2018	91	109
2017	75	55
Prior to 2017	328	352
Revolving loan	1	2
Total	1,856	1,651
Financing Receivables Not Impaired | Normal obligors | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	107	46
2020	17	24
2019	23	132
2018	134	211
2017	155	0
Prior to 2017	114	144
Revolving loan	95	125
Total	645	682
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Large Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	12,277	12,236
2020	5,993	6,641
2019	5,384	5,049
2018	3,994	4,535
2017	3,065	1,679
Prior to 2017	3,670	3,379
Revolving loan	7,517	7,155
Total	41,900	40,674
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Small And Medium Sized Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	551	540
2020	301	397
2019	285	376
2018	248	283
2017	221	171
Prior to 2017	571	494
Revolving loan	531	548
Total	2,708	2,809
Financing Receivables Not Impaired | Normal obligors | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	160	279
2020	188	7
2019	7	33
2018	32	15
2017	5	174
Prior to 2017	2	3
Revolving loan	83	75
Total	477	586
Financing Receivables Not Impaired | Normal obligors | Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	1,536	1,003
2020	265	254
2019	169	151
2018	91	225
2017	19	12
Prior to 2017	4	1
Revolving loan	404	120
Total	2,488	1,766
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	15,317	14,088
2020	3,891	3,571
2019	2,142	3,236
2018	1,954	1,392
2017	1,024	550
Prior to 2017	1,312	1,229
Revolving loan	6,731	5,906
Total	32,371	29,972
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	2	2
2020	1	2
2019	1	2
2018	1	1
2017	1	1
Prior to 2017	3	3
Revolving loan	0	0
Total	9	11
Financing Receivables Not Impaired | Watch obligors | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	8	4
2020	2	4
2019	0	1
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	10	9
Financing Receivables Not Impaired | Watch obligors | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	0
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Large Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	109	146
2020	46	69
2019	50	71
2018	58	66
2017	59	40
Prior to 2017	33	51
Revolving loan	130	128
Total	485	571
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Small And Medium Sized Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	45	44
2020	16	31
2019	26	30
2018	16	32
2017	18	12
Prior to 2017	28	33
Revolving loan	20	25
Total	169	207
Financing Receivables Not Impaired | Watch obligors | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	0
Financing Receivables Not Impaired | Watch obligors | Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	8	5
2020	4	0
2019	4	0
2018	5	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	21	5
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	228	317
2020	101	180
2019	192	74
2018	72	56
2017	43	28
Prior to 2017	50	25
Revolving loan	58	122
Total	744	802
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	0
Financing Receivables Not Impaired | Non Accrual Loans | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	0
Financing Receivables Not Impaired | Non Accrual Loans | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	0
Financing Receivables Not Impaired | Non Accrual Loans | Domestic | Corporate | Large Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	153	61
2020	35	101
2019	61	201
2018	134	45
2017	99	136
Prior to 2017	159	77
Revolving loan	339	178
Total	980	799
Financing Receivables Not Impaired | Non Accrual Loans | Domestic | Corporate | Small And Medium Sized Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	26	18
2020	7	20
2019	16	15
2018	9	11
2017	8	7
Prior to 2017	27	38
Revolving loan	29	32
Total	122	141
Financing Receivables Not Impaired | Non Accrual Loans | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	1
2018	1	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	1	1
Financing Receivables Not Impaired | Non Accrual Loans | Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	1
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	0	1
Financing Receivables Not Impaired | Non Accrual Loans | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	31	35
2020	19	2
2019	13	13
2018	18	17
2017	11	15
Prior to 2017	32	23
Revolving loan	11	10
Total	135	115
Financing Receivables Not Impaired | Non Accrual Loans | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior to 2017	0	0
Revolving loan	0	0
Total	¥ 0	¥ 0

Loans - Credit Quality Inform_2

Loans - Credit Quality Information of Loans Based on MHFG Group's Internal Rating System (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Financing Receivables Impaired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Direct Financing Lease, Lease Receivable	¥ 184	¥ 216

Loans - Impaired Loans Informat

Loans - Impaired Loans Information (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	¥ 1,255	¥ 1,082
Nonaccrual loans without an allowance	77	86
Total nonaccrual loans	1,332	1,168
Interest income recognized	23	14
Domestic
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	1,123	972
Nonaccrual loans without an allowance	73	79
Total nonaccrual loans	1,196	1,051
Interest income recognized	19	13
Domestic | Retail | Housing Loan
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	22	27
Nonaccrual loans without an allowance	17	22
Total nonaccrual loans	39	49
Interest income recognized	1	1
Domestic | Retail | Other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	37	40
Nonaccrual loans without an allowance	18	22
Total nonaccrual loans	55	62
Interest income recognized	1	1
Domestic | Large companies | Corporate
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	961	784
Nonaccrual loans without an allowance	19	16
Total nonaccrual loans	980	800
Interest income recognized	16	9
Domestic | Small and medium sized companies | Corporate
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	103	121
Nonaccrual loans without an allowance	19	19
Total nonaccrual loans	122	140
Interest income recognized	1	2
Foreign
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	132	110
Nonaccrual loans without an allowance	4	7
Total nonaccrual loans	136	117
Interest income recognized	¥ 4	¥ 1

Loans - Troubled Debt Restructu

Loans - Troubled Debt Restructurings Entered Modified Periods by Type of Concession Granted (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	¥ 0	¥ 6
Loan forgiveness or debt to equity swaps charge-offs	141	23
Interest rate reduction and/or postponement of principal and/or interest	791	830
Domestic
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	6
Loan forgiveness or debt to equity swaps charge-offs	141	23
Interest rate reduction and/or postponement of principal and/or interest	725	767
Domestic | Housing Loan | Retail
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	0
Loan forgiveness or debt to equity swaps charge-offs	0	0
Interest rate reduction and/or postponement of principal and/or interest	5	8
Domestic | Other | Retail
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	0
Loan forgiveness or debt to equity swaps charge-offs	0	0
Interest rate reduction and/or postponement of principal and/or interest	19	22
Domestic | Large Companies | Corporate
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	6
Loan forgiveness or debt to equity swaps charge-offs	141	23
Interest rate reduction and/or postponement of principal and/or interest	595	612
Domestic | Small And Medium Sized Companies | Corporate
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	0
Loan forgiveness or debt to equity swaps charge-offs	0	0
Interest rate reduction and/or postponement of principal and/or interest	106	125
Foreign
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	0	0
Loan forgiveness or debt to equity swaps charge-offs	0	0
Interest rate reduction and/or postponement of principal and/or interest	¥ 66	¥ 63

Loans - Payment Defaults Occurr

Loans - Payment Defaults Occurred During Periods with Respect to Loans Modified as Troubled Debt Restructurings within Previous Six Months (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 108	¥ 27
Domestic
Financing Receivable, Modifications [Line Items]
Recorded investment	98	13
Domestic | Corporate | Large companies
Financing Receivable, Modifications [Line Items]
Recorded investment	95	8
Domestic | Corporate | Small and medium sized companies
Financing Receivable, Modifications [Line Items]
Recorded investment	1	3
Domestic | Retail | Housing Loan
Financing Receivable, Modifications [Line Items]
Recorded investment	1	1
Domestic | Retail | Other
Financing Receivable, Modifications [Line Items]
Recorded investment	1	1
Foreign
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 10	¥ 14

Loans - Age Analysis of Past Du

Loans - Age Analysis of Past Due Loans (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
30-59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	¥ 18	¥ 21
30-59 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	18	21
30-59 Days Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
30-59 Days Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
30-59 Days Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	1
30-59 Days Past Due | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	14	15
30-59 Days Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	4	5
30-59 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
30-59 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
60-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	12	10
60-89 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	12	10
60-89 Days Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
60-89 Days Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	3	0
60-89 Days Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	1
60-89 Days Past Due | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	8	8
60-89 Days Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	1	1
60-89 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
60-89 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	83	94
90 Days or More Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	60	65
90 Days or More Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
90 Days or More Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	28	27
90 Days or More Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	9	10
90 Days or More Past Due | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	13	17
90 Days or More Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	10	11
90 Days or More Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
90 Days or More Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	23	29
Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	113	125
Total Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	90	96
Total Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
Total Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	31	27
Total Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	9	12
Total Past Due | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	35	40
Total Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	15	17
Total Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	0	0
Total Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	23	29
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	94,063	90,166
Current | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	57,840	56,936
Current | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	1,866	1,660
Current | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	43,334	42,017
Current | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	2,990	3,145
Current | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	7,472	7,742
Current | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	1,533	1,690
Current | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	645	682
Current | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	36,223	33,230
Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	94,176	90,291
Total | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	57,930	57,032
Total | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	1,866	1,660
Total | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	43,365	42,044
Total | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	2,999	3,157
Total | Domestic | Retail | Housing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	7,507	7,782
Total | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	1,548	1,707
Total | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	645	682
Total | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	¥ 36,246	¥ 33,259

Allowance for Credit Losses o_3

Allowance for Credit Losses on Loans (Changes in Allowance for Loan Losses, Allowance for Loan Losses and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		¥ 809,817		¥ 650,849		¥ 440,855
Provision (credit) for credit losses on loans		90,848		187,599		112,776
Charge-offs		(227,450)	[1]	(59,840)	[1]	(78,801)
Recoveries		10,476		18,754		13,935
Net charge-offs		(216,974)		(41,086)		(64,866)
Others	[2]	17,268		12,455		6,329
Balance at end of fiscal year		700,959		809,817		650,849
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year	[3]	134,397		85,567		110,576
Provision (credit) for credit losses on loans	[3]	44,287		49,729		(20,737)
Charge-offs	[3]	(68,772)	[1]	(23,144)	[1]	(38,374)
Recoveries	[3]	3,414		9,832		10,316
Net charge-offs	[3]	(65,358)		(13,312)		(28,058)
Others	[2],[3]	17,268		12,413		6,329
Balance at end of fiscal year	[3]	130,594		134,397		85,567
Cumulative effect of change in accounting principles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						155,755
Cumulative effect of change in accounting principles | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year	[3]					17,457
Cumulative effect, period of adoption, adjusted balance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						596,610
Cumulative effect, period of adoption, adjusted balance | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year	[3]					128,033
Corporate | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		601,506		481,420		305,458
Provision (credit) for credit losses on loans		51,551		144,998		143,766
Charge-offs		(153,014)	[1]	(32,530)	[1]	(33,625)
Recoveries		5,858		7,618		2,321
Net charge-offs		(147,156)		(24,912)		(31,304)
Others	[2]	0		0		0
Balance at end of fiscal year		505,901		601,506		481,420
Corporate | Cumulative effect of change in accounting principles | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						63,500
Corporate | Cumulative effect, period of adoption, adjusted balance | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						368,958
Retail | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		73,414		83,171		23,219
Provision (credit) for credit losses on loans		(5,413)		(6,895)		(8,558)
Charge-offs		(5,664)	[1]	(4,166)	[1]	(6,802)
Recoveries		1,204		1,304		1,298
Net charge-offs		(4,460)		(2,862)		(5,504)
Others	[2]	0		0		0
Balance at end of fiscal year		63,541		73,414		83,171
Retail | Cumulative effect of change in accounting principles | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						74,014
Retail | Cumulative effect, period of adoption, adjusted balance | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						97,233
Sovereign | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		62		68		88
Provision (credit) for credit losses on loans		(9)		(6)		(99)
Charge-offs		0	[1]	0	[1]	0
Recoveries		0		0		0
Net charge-offs		0		0		0
Others	[2]	0		0		0
Balance at end of fiscal year		53		62		68
Sovereign | Cumulative effect of change in accounting principles | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						79
Sovereign | Cumulative effect, period of adoption, adjusted balance | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						167
Banks and other financial institutions | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		438		623		1,514
Provision (credit) for credit losses on loans		432		(227)		(1,596)
Charge-offs		0	[1]	0	[1]	0
Recoveries		0		0		0
Net charge-offs		0		0		0
Others	[2]	0		42		0
Balance at end of fiscal year		¥ 870		¥ 438		623
Banks and other financial institutions | Cumulative effect of change in accounting principles | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						705
Banks and other financial institutions | Cumulative effect, period of adoption, adjusted balance | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year						¥ 2,219
[1]Charge-offs increased from ¥59,840 million for the fiscal year ended March 31, 2022 to ¥227,450 million for the fiscal year ended March 31, 2023 due mainly to a debt waiver to a domestic corporate borrower.[2]Others includes primarily foreign exchange translation.[3]The majority of total foreign consist of corporate.

Allowance for Credit Losses o_4

Allowance for Credit Losses on Loans (Changes in Allowance for Loan Losses, Allowance for Loan Losses and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment) (parenthetical) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-Offs	¥ 227,450	[1]	¥ 59,840	[1]	¥ 78,801
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-Offs			¥ 59,840
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-Offs	¥ 227,450
[1]Charge-offs increased from ¥59,840 million for the fiscal year ended March 31, 2022 to ¥227,450 million for the fiscal year ended March 31, 2023 due mainly to a debt waiver to a domestic corporate borrower.

Premises and equipment-Summary

Premises and equipment-Summary of Premises and Equipment (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 3,275,098	¥ 3,286,694
Less: Accumulated depreciation and amortization	1,621,210	1,582,627
Premises and equipment—net	1,653,888	1,704,067
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	577,755	571,837
Buildings
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	703,655	737,440
Equipment and furniture
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	378,015	373,825
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	204,835	208,820
Construction in Progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	44,393	21,737
Software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 1,366,445	¥ 1,373,035

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Property, Plant and Equipment [Line Items]
Impairment losses		¥ 13,500	¥ 7,101
Depreciation and amortization	¥ 231,291	220,436	223,164
Global Corporate Company or Retail and Business Banking Company
Property, Plant and Equipment [Line Items]
Impairment losses on real estate			2,275
Entity Wide Software
Property, Plant and Equipment [Line Items]
Impairment losses			3,397
Impairment losses on real estate		12,976
General and Administrative expenses
Property, Plant and Equipment [Line Items]
Impairment losses		433	3,872
Occupancy expenses
Property, Plant and Equipment [Line Items]
Impairment losses		¥ 13,067	¥ 3,229

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Changes in Goodwill) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Goodwill [Line Items]
Balance at beginning of fiscal year	¥ 92,695	¥ 92,695	¥ 92,997
Goodwill acquired	233	0	0
Impairment losses recognized	0	0	(302)
Balance at end of fiscal year	92,928	92,695	92,695
Gross amount of goodwill	163,209	161,993	167,552
Accumulated impairment losses	¥ 70,281	¥ 69,298	¥ 74,857

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Gross Carrying Amount, Accumulated Amortization and Net Carrying Amount of Intangible Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Intangible Assets by Major Class [Line Items]
Gross carrying amount		¥ 133,007	¥ 128,447
Gross carrying amount		7,859	8,006
Net carrying amount		7,859	8,006
Gross carrying amount		140,866	136,453
Accumulated amortization		96,185	88,514
Net carrying amount		36,822	39,933
Net carrying amount		44,681	47,939
Customer relationships
Intangible Assets by Major Class [Line Items]
Gross carrying amount	[1]	130,124	126,979
Accumulated amortization	[1]	94,777	87,277
Net carrying amount	[1]	35,347	39,702
Other
Intangible Assets by Major Class [Line Items]
Gross carrying amount		2,883	1,468
Accumulated amortization		1,408	1,237
Net carrying amount		¥ 1,475	¥ 231
[1]Customer relationships were mainly acquired in connection with the merger of MHSC and Shinko on May 7, 2009 and the integration among asset management companies on October 1, 2016. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information.

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets amortization expense recognized	¥ 7,706	¥ 7,961	¥ 8,513

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets (Estimated Aggregate Amortization Expense in Respect of Intangible Assets) (Detail) ¥ in Millions	Mar. 31, 2023 JPY (¥)
Finite-Lived Intangible Assets [Line Items]
2024	¥ 7,210
2025	6,698
2026	6,194
2027	5,564
2028	¥ 2,559

Pledged Assets and Collateral_2

Pledged Assets and Collateral (Amounts Pledged as Collateral for Borrowings and for Other Purposes) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Financial Instruments Owned and Pledged as Collateral [Line Items]
Interest-bearing deposits in other banks	¥ 92	¥ 75
Trading account assets	7,830	5,426
Investments	12,452	8,091
Other assets	2,059	3,023
Total	31,148	25,671
Asset Pledged as Collateral without Right [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Loans	¥ 8,715	¥ 9,056

Pledged Assets and Collateral_3

Pledged Assets and Collateral (Associated Liabilities Collateralized by Pledged Assets) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Deposits	¥ 988	¥ 910
Payables under repurchase agreements	10,542	5,864
Payables under securities lending transactions	721	645
Other short-term borrowings	1,003	5,113
Long-term debt	2,173	542
Total	¥ 15,427	¥ 13,074

Pledged Assets and Collateral -

Pledged Assets and Collateral - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Reserve funds maintained with the BOJ	¥ 64,993	¥ 48,897
Reserve funds requires to be maintained by MHFG Group	1,701	1,678
Fair value collateral received that can be sold or repledged	15,529	16,632
Fair value collateral received that can be sold or repledged, value of collateral sold or repledged	¥ 13,379	¥ 14,865

Deposits (Balance and Remaining

Deposits (Balance and Remaining Maturities of Time Deposits and Certificates of Deposit Issued by Domestic and Foreign Offices) (Detail) ¥ in Millions	Mar. 31, 2023 JPY (¥)
Deposits From Banking Clients [Line Items]
Total	¥ 57,774,061
Bank Time Deposits Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	18,355,950
Due after one year through two years	1,376,534
Due after two years through three years	976,153
Due after three years through four years	240,172
Due after four years through five years	314,567
Due after five years	219,492
Total	21,482,868
Certificates Of Deposit Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	6,056,971
Due after one year through two years	174,580
Due after two years through three years	500
Due after three years through four years	0
Due after four years through five years	0
Due after five years	0
Total	6,232,051
Bank Time Deposits Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	22,436,741
Due after one year through two years	25,120
Due after two years through three years	15,999
Due after three years through four years	23,404
Due after four years through five years	160
Due after five years	1,421
Total	22,502,845
Certificates Of Deposit Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	7,185,063
Due after one year through two years	281,524
Due after two years through three years	89,710
Due after three years through four years	0
Due after four years through five years	0
Due after five years	0
Total	7,556,297
Time deposits
Deposits From Banking Clients [Line Items]
Total	43,985,713
Certificates of deposit
Deposits From Banking Clients [Line Items]
Total	13,788,348
Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	24,412,921
Due after one year through two years	1,551,114
Due after two years through three years	976,653
Due after three years through four years	240,172
Due after four years through five years	314,567
Due after five years	219,492
Total	27,714,919
Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	29,621,804
Due after one year through two years	306,644
Due after two years through three years	105,709
Due after three years through four years	23,404
Due after four years through five years	160
Due after five years	1,421
Total	¥ 30,059,142

Deposits (Estimated amounts Of

Deposits (Estimated amounts Of Uninsured Time Deposits And Certificates Of Deposit Issued By Domestic And Foreign Offices) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit	¥ 20,209	¥ 20,885
Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit	30,059	24,926
Time deposits | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit	13,977	10,437
Time deposits | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit	22,503	18,505
Certificates of deposit | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit	6,232	10,448
Certificates of deposit | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit	¥ 7,556	¥ 6,421

Deposits - Additional Informati

Deposits - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Deposits From Banking Clients [Line Items]
Aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances	¥ 586	¥ 585

Short-Term Borrowings and Lon_3

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Short-term Debt [Line Items]
Borrowings from the Bank of Japan		¥ 876,036	¥ 5,105,225
Other		262,040	148,518
Total		3,397,329	7,566,771
Mizuho Financial Group Inc
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[1],[2]	2,218,111	2,266,360
Consolidated VIEs
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[1]	41,142	46,668
Total		¥ 187,852	¥ 53,668
[1]Short-term notes are issued under the laws of Japan in the form of commercial paper.[2]The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥1,775,860 million and ¥490,500 million, respectively, at March 31, 2022, and ¥1,782,111 million and ¥436,000 million, respectively, at March 31, 2023.

Short-Term Borrowings and Lon_4

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Parenthetical) (Detail) - Mizuho Financial Group Inc - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Short-term Debt [Line Items]
Commercial paper	¥ 1,782,111	¥ 1,775,860
Short-term notes	¥ 436,000	¥ 490,500

Short-Term Borrowings and Lon_5

Short-Term Borrowings and Long-Term Debt (Long-Term Debt with Original Maturities of More than One Year) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Debt Instrument [Line Items]
Obligations under finance leases	¥ 6,863	¥ 4,621
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Obligations under finance leases	Obligations under finance leases
Loan participation borrowings	¥ 245,176	¥ 220,312
Senior borrowings and bonds	11,245,475	8,600,493
Subordinated borrowings and bonds	3,395,509	3,752,790
Total	¥ 14,893,023	¥ 12,578,216

Short-Term Borrowings and Lon_6

Short-Term Borrowings and Long-Term Debt (Interest Rates and Maturities of Senior Borrowings and Bonds, and Subordinated Borrowings and Bonds) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Debt Instrument [Line Items]
Borrowings and bonds		¥ 14,640,984	¥ 12,353,283
Senior borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		11,245,475	8,600,493
Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		2,819,085	1,032,194
Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		3,692,271	3,581,901
Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		1,948,714	1,223,991
Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		569,173	582,430
Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		2,058,714	2,001,616
Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		157,518	178,361
Subordinated borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		3,395,509	3,752,790
Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		2,961,504	3,171,343
Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		¥ 434,005	¥ 581,447
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0%
Maturities, Start	[2]	2023-04
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0%
Maturities, Start	[2]	2023-04
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0%
Maturities, Start	[2]	2023-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0%
Maturities, Start	[2]	2023-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0%
Maturities, Start	[2]	2023-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0.10%
Maturities, Start	[2]	2023-04
Minimum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.39%
Maturities, Start	[2]	2023-06
Minimum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	2.56%
Maturities, Start	[2]	2024-03
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	6.20%
Maturities, End	[2]	2051-06
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	5.75%
Maturities, End	[2]	2048-03
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	5.92%
Maturities, End	[2]	2041-05
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	25%
Maturities, End	[2]	2081-09
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	32.80%
Maturities, End	[2]	2068-02
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	12%
Maturities, End	[2]	2041-09
Maximum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	4.26%
Maximum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	4.70%
Maturities, End	[2]	2031-09
[1]The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2023.[2]Maturity information disclosed is the range of maturities at March 31, 2023.

Short-Term Borrowings and Lon_7

Short-Term Borrowings and Long-Term Debt (Contractual Maturities of Long-Term Debt) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Debt Instrument [Line Items]
2024	¥ 1,177,938
2025	3,757,328
2026	702,968
2027	1,428,227
2028	1,291,313
2029 and thereafter	6,535,249
Total	¥ 14,893,023	¥ 12,578,216

Other Assets and Liabilities (D

Other Assets and Liabilities (Details of Other Assets and Liabilities) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Other assets:
Receivables from brokers, dealers and customers for securities transactions		¥ 4,469,286	¥ 3,049,874
Other		468,344	557,842
Collateral pledged for derivative transactions		988,881	1,549,483
Margins provided for futures contracts		183,747	466,531
Other		890,350	1,006,849
Prepaid pension cost		768,998	762,147
Right-of-use assets	[1]	549,668	570,171
Security deposits		83,343	91,766
Loans held for sale		228,995	156,639
Other	[2]	1,069,348	775,940
Total		9,700,960	8,987,242
Other liabilities:
Payables to brokers, dealers and customers for securities transactions		1,799,116	1,406,965
Other		527,493	494,538
Guaranteed trust principal	[3]	817,448	810,776
Lease liabilities	[1]	¥ 571,087	¥ 593,339
Operating Lease, Liability, Statement of Financial Position [Extensible List]		Total	Total
Collateral accepted for derivative transactions		¥ 1,008,083	¥ 1,075,591
Margins accepted for futures contracts		81,925	327,883
Unearned income		112,077	113,181
Other		1,399,466	1,437,949
Total		¥ 6,316,695	¥ 6,260,222
[1]Right-of-use assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.[2]As of March 31, 2023, the MHFG Group included premises and equipment classified as held for sale in Other.[3]Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 23 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred Stock (Composition of

Preferred Stock (Composition of Preferred Stock) (Detail) - shares	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Class Fourteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	90,000,000	90,000,000	90,000,000
Number of shares Issued	0	0	0
Class Fifteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	90,000,000	90,000,000	90,000,000
Number of shares Issued	0	0	0
Class Sixteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	150,000,000	150,000,000	150,000,000
Number of shares Issued	0	0	0

Common Stock - Summary of Chang

Common Stock - Summary of Changes in Number of Issued Shares of Common Stock (Detail) - shares	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Class of Stock [Line Items]
Balance at beginning of fiscal year	2,539,249,894	2,539,249,894	2,539,249,894
Issuance of new shares of common stock due to exercise of stock acquisition rights	0	0	0
Balance at end of fiscal year	2,539,249,894	2,539,249,894	2,539,249,894

Dividends - Additional Informat

Dividends - Additional Information (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2023 JPY (¥)
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital stock	¥ 2,256,768
Capital surplus	1,196,660
Retained earnings	¥ 2,214,748
Description of dividend payment restrictions	Pursuant to the Companies Act, in making a distribution of retained earnings, an entity must set aside in its legal reserve an amount equal to one-tenth of the amount of retained earnings so distributed, until its legal reserve reaches one-quarter of its capital stock.
Legal reserve	¥ 1,201,010
Maximum amount available for dividends under Company Law and the Banking Law	2,203,318
Japan Gaap Additional PaidIn Capital [Member]
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	1,196,660
Japan Gaap Retained Earnings [Member]
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	¥ 4,350

Accumulated other comprehensi_3

Accumulated other comprehensive income (loss), net of tax Changes in Each Component of AOCI) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		¥ 9,442,231	¥ 9,688,157
Less: reclassification adjustments for losses (gains) included in net income		(15,803)
Change during year		209,687	126,593	¥ 327,108
Balance at end of fiscal year		9,725,134	9,442,231	9,688,157
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	[1]	440,112	318,114	(9,494)
Change during year	[1]	209,283	121,998	327,608
Balance at end of fiscal year	[1]	649,395	440,112	318,114
Net unrealized gains (losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		(25,046)	(8,173)	(19,592)
Unrealized gains (losses) during year		(7,472)	(35,922)	(4,911)
Less: reclassification adjustments for losses (gains) included in net income		1,434	19,049	16,330
Change during year		(6,038)	(16,873)	11,419
Balance at end of fiscal year		(31,084)	(25,046)	(8,173)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		94,104	(86,873)	(109,872)
Foreign currency translation adjustments during year		133,556	181,722	22,704
Less: reclassification adjustments for losses (gains) included in net income		0	(745)	295
Change during year		133,556	180,977	22,999
Balance at end of fiscal year		227,660	94,104	(86,873)
Defined benefit plan adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		355,355	397,153	69,455
Unrealized gains (losses) during year		86,326	(22,825)	331,668
Less: reclassification adjustments for losses (gains) included in net income		(18,004)	(18,973)	(3,970)
Change during year		68,322	(41,798)	327,698
Balance at end of fiscal year		423,677	355,355	397,153
Accumulated Own Credit Risk Adjustment Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		15,699	16,007	50,515
Unrealized gains (losses) during year		12,688	(858)	(30,345)
Less: reclassification adjustments for losses (gains) included in net income		755	550	(4,163)
Change during year		13,443	(308)	(34,508)
Balance at end of fiscal year		¥ 29,142	¥ 15,699	¥ 16,007
[1]The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 16 “Accumulated other comprehensive income (loss), net of tax.”

Accumulated other comprehensi_4

Accumulated other comprehensive income (loss), net of tax (Amounts Reclassified Out of Accumulated Other Comprehensive Income into Net Income) (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2023 JPY (¥)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	¥ 23,012	[1]
Tax effect	(7,209)	[2]
Net of tax before allocation to noncontrolling interests	15,803
Net of tax attributable to noncontrolling interests	12	[2]
Net of tax attributable to MHFG shareholders	15,815
Accumulated Net unrealized gains (losses) on available-for-sale securities | Investment gains (losses) net and Other noninterest income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	(1,739)	[1]
Tax effect	305	[2]
Net of tax before allocation to noncontrolling interests	(1,434)
Net of tax attributable to noncontrolling interests	0	[2]
Net of tax attributable to MHFG shareholders	(1,434)
Accumulated Defined Benefit Plans Adjustment | Salaries and employee benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	25,840	[1]
Tax effect	(7,848)	[2]
Net of tax before allocation to noncontrolling interests	17,992
Net of tax attributable to noncontrolling interests	12	[2]
Net of tax attributable to MHFG shareholders	18,004
Accumulated Own Credit Risk Adjustment | Other Noninterest Income (Expenses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	(1,089)	[1]
Tax effect	334	[2]
Net of tax before allocation to noncontrolling interests	(755)
Net of tax attributable to noncontrolling interests	0	[2]
Net of tax attributable to MHFG shareholders	¥ (755)
[1]The financial statement line item in which the amounts in the before tax column are reported in the consolidated statements of income is listed to the right of the table.[2]The financial statement line items in which the amounts in the tax effect and the net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense (benefit) and Net income (loss), respectively.

Regulatory Matters (Capital Req

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Detail)		12 Months Ended
		Mar. 31, 2023		Mar. 31, 2022	Mar. 31, 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%		2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%			1%
March 2022
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		8%
Capital conservation buffer		2.50%
Countercyclical capital buffer		0.01%	[1]	0.01%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%	[2]	1%
Minimum Leverage Ratio		3%
March 2022 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		4.50%
March 2022 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		6%
March 2023
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		8%
Capital conservation buffer		2.50%
Countercyclical capital buffer	[1]	0.06%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[2]	1%
Minimum Leverage Ratio	[3]	3.50%
March 2023 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		4.50%
March 2023 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		6%
March 2024
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		8%
Capital conservation buffer		2.50%
Countercyclical capital buffer	[1]	0.06%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[2]	1%
Minimum Leverage Ratio	[3]	3.50%
March 2024 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		4.50%
March 2024 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		6%
March 2025
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		8%
Capital conservation buffer		2.50%
Countercyclical capital buffer	[1]	0.06%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[2]	1%
Minimum Leverage Ratio	[3]	3.70%
March 2025 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		4.50%
March 2025 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital		6%
[1]Figures assume that the countercyclical capital buffer will continue to be 0.06% after March 2024.[2]Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.[3]This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB under the finalized Basel III reforms.

Regulatory Matters (Capital R_2

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Parenthetical) (Detail)		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%	1%
March 2023
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Countercyclical capital buffer	[1]	0.06%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[2]	1%
March 2024
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Countercyclical capital buffer	[1]	0.06%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[2]	1%
March 2024 | Basel III
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Leverage ratio buffer		50%
March 2026
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%
[1]Figures assume that the countercyclical capital buffer will continue to be 0.06% after March 2024.[2]Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.

Regulatory Matters (Capital Ade

Regulatory Matters (Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023		Mar. 31, 2022	Mar. 31, 2019
Common Equity Tier 1 capital:
Actual		¥ 2,256,768
Required, ratio		120%
Leverage Ratio:
Required, ratio					3%
Mizuho Financial Group Inc | Consolidated
Common Equity Tier 1 capital:
Required, amount	[1]	¥ 5,676,000		¥ 5,184,000
Actual		8,315,000		8,067,000
Required, amount	[1]	6,733,000		6,155,000
Actual		¥ 9,803,000		¥ 9,713,000
Required, ratio	[1]	9.56%		9.51%
Actual		13.91%		15%
Required, amount	[1]	¥ 8,142,000		¥ 7,450,000
Actual		¥ 11,306,000		¥ 11,351,000
Required, ratio	[1]	11.56%		11.51%
Actual		16.05%		17.53%
Required, amount	[2]	¥ 7,680,000		¥ 6,389,000
Actual	[2]	¥ 9,803,000		¥ 9,713,000
Common Equity Tier 1 capital:
Required, ratio	[1]	8.06%		8.01%
Actual		11.80%		12.46%
Leverage Ratio:
Required, ratio	[2]	3.50%	[3]	3%
Actual	[2]	4.46%		4.56%
Mizuho Bank Limited | Consolidated
Common Equity Tier 1 capital:
Required, amount		¥ 2,941,000		¥ 2,683,000
Actual		6,873,000		6,968,000
Required, amount		3,922,000		3,578,000
Actual		¥ 8,356,000		¥ 8,604,000
Required, ratio		6%		6%
Actual		12.78%		14.42%
Required, amount		¥ 5,229,000		¥ 4,771,000
Actual		¥ 9,769,000		¥ 10,150,000
Required, ratio		8%		8%
Actual		14.94%		17.02%
Required, amount	[2]	¥ 6,216,000		¥ 5,971,000
Actual	[2]	¥ 8,356,000		¥ 8,604,000
Common Equity Tier 1 capital:
Required, ratio		4.50%		4.50%
Actual		10.51%		11.68%
Leverage Ratio:
Required, ratio	[2]	3%		3%
Actual	[2]	4.03%		4.32%
Mizuho Bank Limited | Non-consolidated
Common Equity Tier 1 capital:
Required, amount		¥ 2,751,000		¥ 2,528,000
Actual		5,981,000		6,293,000
Required, amount		3,668,000		3,370,000
Actual		¥ 7,450,000		¥ 7,919,000
Required, ratio		6%		6%
Actual		12.18%		14.09%
Required, amount		¥ 4,891,000		¥ 4,494,000
Actual		¥ 8,853,000		¥ 9,483,000
Required, ratio		8%		8%
Actual		14.48%		16.88%
Required, amount	[2]	¥ 5,767,000		¥ 5,570,000
Actual	[2]	¥ 7,450,000		¥ 7,919,000
Common Equity Tier 1 capital:
Required, ratio		4.50%		4.50%
Actual		9.78%		11.20%
Leverage Ratio:
Required, ratio	[2]	3%		3%
Actual	[2]	3.87%		4.26%
Mizuho Trust & Banking Company Limited | Consolidated
Common Equity Tier 1 capital:
Required, amount		¥ 77,000		¥ 79,000
Actual		444,000		442,000
Required, amount		102,000		105,000
Actual		¥ 444,000		¥ 442,000
Required, ratio		6%		6%
Actual		25.94%		25.18%
Required, amount		¥ 137,000		¥ 140,000
Actual		¥ 444,000		¥ 442,000
Required, ratio		8%		8%
Actual		25.95%		25.18%
Required, amount	[2]	¥ 125,000		¥ 130,000
Actual	[2]	¥ 444,000		¥ 442,000
Common Equity Tier 1 capital:
Required, ratio		4.50%		4.50%
Actual		25.94%		25.18%
Leverage Ratio:
Required, ratio	[2]	3%		3%
Actual	[2]	10.61%		10.20%
Mizuho Trust & Banking Company Limited | Non-consolidated
Common Equity Tier 1 capital:
Required, amount		¥ 76,000		¥ 78,000
Actual		425,000		425,000
Required, amount		101,000		104,000
Actual		¥ 425,000		¥ 425,000
Required, ratio		6%		6%
Actual		25.10%		24.40%
Required, amount		¥ 135,000		¥ 139,000
Actual		¥ 425,000		¥ 425,000
Required, ratio		8%		8%
Actual		25.11%		24.40%
Required, amount	[2]	¥ 122,000		¥ 126,000
Actual	[2]	¥ 425,000		¥ 425,000
Common Equity Tier 1 capital:
Required, ratio		4.50%		4.50%
Actual		25.10%		24.40%
Leverage Ratio:
Required, ratio	[2]	3%		3%
Actual	[2]	10.44%		10.09%
[1]The required ratios disclosed above, at March 31, 2022, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01% and the additional loss absorbency requirements for G-SIBs and D-SIBs of 1.0%. The required ratios disclosed above, at March 31, 2023, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.06% and the additional loss absorbency requirements for G-SIBs and D-SIBs of 1.0%. These are all in addition to the regulatory minima. The respective required amounts are determined by applying the ratios to the sum of the risk weighted assets and certain other risk amounts.[2]The required and actual amounts disclosed above at March 31, 2022 and 2023 exclude amounts of deposits to the Bank of Japan.[3]The required ratio disclosed above, at March 31, 2023, includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB under the finalized Basel III reforms.

Regulatory Matters (Capital A_2

Regulatory Matters (Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency) (Parenthetical) (Detail)		12 Months Ended
		Mar. 31, 2023		Mar. 31, 2022	Mar. 31, 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%		2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%			1%
March 2022
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1%	[1]	1%
Countercyclical capital buffer		0.01%	[2]	0.01%
March 2023
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs	[1]	1%
Countercyclical capital buffer	[2]	0.06%
Leverage ratio buffer		0.50
[1]Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.[2]Figures assume that the countercyclical capital buffer will continue to be 0.06% after March 2024.

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	120%
Leverage ratio		3%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1%	1%
Description of regulatory actions for not maintaining the minimum capital ratio concerning securities subsidiaries	A capital ratio of less than 140% will call for regulatory reporting and a capital ratio of less than 100% may lead to a temporary suspension of all or part of the business operations and further, to the cancellation of the license to act as a securities broker and dealer.
Maximum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	2.50%
Minimum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	0%
Minimum | Regulatory reporting
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	140%
Minimum | Temporary suspension
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	100%
Basel III
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Tier 1 capital ratio	6%
Common Equity Tier 1	4.50%
Basel III | Minimum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	8%

Earnings Per Common Share (Comp

Earnings Per Common Share (Computation of Basic and Diluted Earnings Per Common Share) (Detail) - JPY (¥) ¥ / shares in Units, shares in Thousands, ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Net income (loss):
Net income (loss) attributable to MHFG common shareholders		¥ (14,009)	¥ (104,722)	¥ 581,765
Effect of dilutive securities
Effect of dilutive securities		0	0	0
Net income (loss) attributable to common shareholders after assumed conversions		¥ (14,009)	¥ (104,722)	¥ 581,765
Shares:
Weighted average common shares outstanding		2,536,596	2,537,051	2,537,513
Effect of dilutive securities:
Stock options and the common shares of MHFG under the stock compensation programs	[1]	0	0	89
Weighted average common shares after assumed conversions		2,536,596	2,537,051	2,537,602
Earnings per common share:
Basic net income (loss) per common share		¥ (5.52)	¥ (41.28)	¥ 229.27
Diluted net income (loss) per common share	[1]	¥ (5.52)	¥ (41.28)	¥ 229.26
[1]For the fiscal years ended March 31, 2021, 2022 and 2023, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects. In addition, for the fiscal years ended March 31, 2022 and 2023, the computation of diluted earnings per common share did not assume exercise of stock options, as the effect of such exercise would be antidilutive due to net loss.

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense (Benefit)) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Current:
Domestic	¥ 22,015	¥ 42,401	¥ 81,023
Foreign	156,969	71,947	78,992
Total current tax expense	178,984	114,348	160,015
Deferred:
Domestic	(146,721)	(256,093)	55,927
Foreign	2,879	728	(5,226)
Total deferred tax expense (benefit)	(143,842)	(255,365)	50,701
Total income tax expense (benefit)	¥ 35,142	¥ (141,017)	¥ 210,716

Income Taxes (Detailed Amounts

Income Taxes (Detailed Amounts of Tax Effects of Items Recorded Directly in Equity) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Net unrealized gains (losses) on available-for-sale securities:
Unrealized gains (losses)	¥ (4,276)	¥ (16,489)	¥ (2,810)
Less: reclassification adjustments	305	8,504	7,195
Total	(3,971)	(7,985)	4,385
Defined benefit plan adjustments:
Unrealized gains (losses)	37,661	(9,020)	143,653
Less: reclassification adjustments	(7,848)	(7,748)	(1,424)
Total	29,813	(16,768)	142,229
Own credit risk adjustments:
Unrealized gains (losses)	5,630	1,745	919
Less: reclassification adjustments	334	271	(1,911)
Total	5,964	2,016	(992)
Total tax effect before allocation to noncontrolling interests	¥ 31,806	¥ (22,737)	¥ 145,622

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Income Taxes [Line Items]
Net operating loss carryforwards	[1]	¥ 500,000
Changes that directly affected Income tax expense			¥ 16,196	¥ (39,410)
Change in valuation allowance		39,754	17,818	3,282
Unrecognized tax benefits, that would affect effective tax rate		7,043	5,245	4,401
Unrecognized tax benefits, interest and penalties		2,286	¥ 1,812	¥ 1,463
Mizuho Securities Company Limited | Japan
Income Taxes [Line Items]
Net operating loss carryforwards		156,000
Mizuho Financial Group Inc
Income Taxes [Line Items]
Undistributed earnings		349,000
Deferred tax liabilities		¥ 36,000
[1]Net operating loss carryforwards related to Japanese local taxes recorded at MHFG in the fiscal year ended March 31, 2022 in the amount of ¥500 billion (tax effected ¥24 billion) are not included in the table. The net operating loss carryforwards is fully offset by valuation allowance and will mostly expire during the fiscal year ending March 31, 2032.

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense) (Detail)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022		Mar. 31, 2021
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate	30.62%	30.62%		30.62%
Income not subject to tax	(14.23%)	4.21%		(0.72%)
Expenses not deductible for tax purposes	1.63%	(0.34%)		0.07%
Tax rate differentials of subsidiaries	(12.95%)	3.31%		(0.90%)
Change in valuation allowance	(5.95%)	(6.68%)	[1]	(3.83%)
Change in undistributed earnings of subsidiaries	8.32%	(2.22%)		0.34%
Noncontrolling interest income (loss) of consolidated VIEs	(15.48%)	(2.10%)		(6.83%)
Effect of enacted change in tax rates	(0.05%)	0.01%		(0.02%)
Reversal of outside basis differences	0%	50.59%	[1]	0%
Foreign tax credit and payments	55.14%	(16.59%)		0.16%
Income excluded from taxable income of enterprise tax	(14.96%)	2.86%		(0.49%)
Controlled foreign company rules	2.68%	(1.66%)		0.71%
Other	16.04%	(3.86%)		1.37%
Effective income tax rate	50.81%	58.15%		20.48%
[1]These amounts for the fiscal year ended March 31, 2022 mainly represent the reversal of an outside basis difference related to the share buyback conducted by MHSC in response to improving the capital position and aligning to the MHFG Group’s capital policy and the related increase in the valuation allowance.

Income Taxes (Components of Net

Income Taxes (Components of Net Deferred Tax Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021	Mar. 31, 2020
Deferred tax assets:
Allowance for credit losses		¥ 270,423		¥ 292,277
Lease liabilities		176,304		183,537
Trading securities		173,793		118,242
Derivative financial instruments		161,141		52,321
Premises and equipment		53,531		65,051
Available-for-sale securities		13,020		8,313
Net operating loss carryforwards	[1],[2]	168,387		183,410
Other		255,557		223,564
Deferred Tax Assets, Gross, Total		1,272,156		1,126,715
Valuation allowance		(198,800)	[1],[2]	(163,164)	[1],[2]	¥ (129,150)	¥ (165,278)
Deferred tax assets, net of valuation allowance		1,073,356		963,551
Deferred tax liabilities:
Investments		264,147		213,398
Prepaid pension cost and accrued pension liabilities		224,173		221,256
Right-of-use assets		169,353		176,591
Other		54,515		104,020
Deferred tax liabilities		712,188		715,265
Net deferred tax assets		¥ 361,168		¥ 248,286
[1]The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥24,675 million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[2]The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Components of N_2

Income Taxes (Components of Net Deferred Tax Assets) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021	Mar. 31, 2020
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Net operating loss carryforwards	[1],[2]	¥ 168,387		¥ 183,410
Valuation allowance		198,800	[1],[2]	163,164	[1],[2]	¥ 129,150	¥ 165,278
Mizuho Securities Company Limited
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Net operating loss carryforwards		49,393		73,736
Valuation allowance		43,488		46,734
Mizuho Financial Group, Inc. [Member]
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Net operating loss carryforwards		24,978		26,633
Valuation allowance		¥ 24,978		¥ 24,675
[1]The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥24,675 million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[2]The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Breakdown of Net

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023		Mar. 31, 2022
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1],[2]	¥ 168,387		¥ 183,410
Operating loss, Valuation allowance		(152,000)		(152,000)
Deferred tax assets, net of valuation allowance		16,000		31,000
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		89,000	[3]	106,000	[4]
Operating loss, Valuation allowance		(75,000)	[3]	(77,000)	[4]
Deferred tax assets, net of valuation allowance		14,000	[3]	29,000	[4]
United States of America
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		1,000		1,000
Deferred tax assets, net of valuation allowance		1,000		1,000
United Kingdom
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[5]	77,000		75,000
Operating loss, Valuation allowance	[5]	(77,000)		(75,000)
Others
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		1,000		1,000
Deferred tax assets, net of valuation allowance		¥ 1,000		¥ 1,000
[1]The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥24,675 million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[2]The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[3]¥49 billion of the Japan deferred tax assets of ¥89 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥25 billion of the Japan deferred tax assets of ¥89 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032.[4]¥74 billion of the Japan deferred tax assets of ¥106 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥27 billion of the Japan deferred tax assets of ¥106 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032.[5]The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes.

Income Taxes (Breakdown of Ne_2

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023		Mar. 31, 2022
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1],[2]	¥ 168,387		¥ 183,410
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		89,000	[3]	106,000	[4]
Mizuho Securities Company Limited
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		49,393		73,736
Mizuho Securities Company Limited | Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 49,000		¥ 74,000
Operating loss carryforwards, expiration date		Mar. 31, 2026		Mar. 31, 2026
Mizuho Financial Group, Inc. [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 24,978		¥ 26,633
Mizuho Financial Group, Inc. [Member] | Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 25,000		¥ 27,000
Operating loss carryforwards, expiration date		Mar. 31, 2032		Mar. 31, 2032
[1]The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥24,675 million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[2]The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[3]¥49 billion of the Japan deferred tax assets of ¥89 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥25 billion of the Japan deferred tax assets of ¥89 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032.[4]¥74 billion of the Japan deferred tax assets of ¥106 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. ¥27 billion of the Japan deferred tax assets of ¥106 billion is related to MHFG, which is substantially offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032.

Income Taxes (Roll-forward of V

Income Taxes (Roll-forward of Valuation Allowance) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021
Valuation Allowance [Line Items]
Balance at beginning of fiscal year	¥ 163,164	[1],[2]	¥ 129,150		¥ 165,278
Changes that directly affected Income tax expense	(4,118)		16,196		(39,410)
Expiration of net operating loss carryforwards	0
Others	39,754		17,818		3,282
Total	39,754		17,818		3,282
Balance at end of fiscal year	¥ 198,800	[1],[2]	¥ 163,164	[1],[2]	¥ 129,150
[1]The amount includes ¥26,633 million and ¥24,978 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥24,675 million and ¥24,978 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.[2]The amount includes ¥73,736 million and ¥49,393 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2022 and 2023, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥46,734 million and ¥43,488 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Net Operating Los

Income Taxes (Net Operating Losses Carryforwards by Expiration Date) (Detail) ¥ in Billions	Mar. 31, 2023 JPY (¥)	[1]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	¥ 500
2024
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2025
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2026
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	156
2027
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	3
2028
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2029 and thereafter
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	¥ 341	[2]
[1]Net operating loss carryforwards related to Japanese local taxes recorded at MHFG in the fiscal year ended March 31, 2022 in the amount of ¥500 billion (tax effected ¥24 billion) are not included in the table. The net operating loss carryforwards is fully offset by valuation allowance and will mostly expire during the fiscal year ending March 31, 2032.[2]Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom.

Income Taxes (Net Operating L_2

Income Taxes (Net Operating Losses Carryforwards by Expiration Date) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2022	Mar. 31, 2023
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	[1]		¥ 500
Mizuho Financial Group, Inc. [Member] | National Tax Agency, Japan [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		¥ 500
Net operating loss carryforwards tax effected		¥ 24
Operating loss carryforwards, expiration date		Mar. 31, 2032
[1]Net operating loss carryforwards related to Japanese local taxes recorded at MHFG in the fiscal year ended March 31, 2022 in the amount of ¥500 billion (tax effected ¥24 billion) are not included in the table. The net operating loss carryforwards is fully offset by valuation allowance and will mostly expire during the fiscal year ending March 31, 2032.

Income Taxes (Roll-forward of U

Income Taxes (Roll-forward of Unrecognized Tax Benefits) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Operating Loss Carryforwards [Line Items]
Total unrecognized tax benefits at beginning of fiscal year	¥ 5,245	¥ 4,401	¥ 3,374
Gross amount of increases (decreases) related to positions taken during prior years	(438)	(576)	455
Gross amount of increases related to positions taken during the current year	1,748	954	524
Amount of decreases related to settlements	0
Foreign exchange translation	488	466	48
Total unrecognized tax benefits at end of fiscal year	¥ 7,043	¥ 5,245	¥ 4,401

Pension and Other Employee Be_3

Pension and Other Employee Benefit Plans (Components of Net Periodic Costs of Severance Indemnities and Pension Plans) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the fiscal year	¥ 30,460	¥ 33,190	¥ 39,672
Interest costs on projected benefit obligations	6,917	5,636	5,790
Expected return on plan assets	(36,322)	(37,051)	(41,887)
Amortization of prior service cost (benefits)	(4,854)	(4,820)	(2,378)
Amortization of net actuarial loss (gain)	(19,453)	(20,485)	1,671
Special termination benefits	7,269	10,791	9,569
Loss (gain) on settlement	0	0	(3,945)
Net periodic benefit cost	¥ (15,983)	¥ (12,739)	¥ 8,492
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense, Deposits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Investment Income, Interest

Pension and Other Employee Be_4

Pension and Other Employee Benefit Plans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, costs recognized in respect of contributions to the plans	¥ 7,395	¥ 3,981	¥ 4,510
Aggregated accumulated benefit obligations	¥ 1,287,692	¥ 1,377,739
Description of requirements for lump-sum severance indemnities	Employees with service in excess of one year are qualified to receive lump-sum severance indemnities.
Pension plan, contribution expected to be paid during the next fiscal year	¥ 32,000

Pension and Other Employee Be_5

Pension and Other Employee Benefit Plans (Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) Before-Tax) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	¥ 122,331	¥ (36,796)
Amortization of net actuarial loss (gain)	(19,453)	(20,485)
Prior service benefits (cost)		(1)
Amortization of prior service cost (benefits)	(4,854)	(4,820)
Total recognized in other comprehensive income (loss) before-tax	¥ 98,024	¥ (62,102)

Pension and Other Employee Be_6

Pension and Other Employee Benefit Plans (Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost) (Detail)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Discount rates	0.82%	0.52%	0.38%
Rates of increase in future compensation levels	2%	2%	1.80%
Interest credit rates	4.45%	4.39%	4.38%
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Discount rates	0.52%	0.38%	0.37%
Rates of increase in future compensation levels	2%	1.80%
Expected rates of return on plan assets	1.72%	1.54%	1.79%
Interest credit rates	4.39%	4.38%	4.95%
Minimum
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Rates of increase in future compensation levels			1.80%
Maximum
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Rates of increase in future compensation levels			4.80%

Pension and Other Employee Be_7

Pension and Other Employee Benefit Plans (Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Change in benefit obligations:
Benefit obligations at beginning of fiscal year		¥ 1,377,739	¥ 1,437,843
Service cost		30,460	33,190	¥ 39,672
Interest cost		6,917	5,636	5,790
Plan participants' contributions		1,053	1,089
Amendments			1
Actuarial loss (gain)		(48,856)	(19,939)
Foreign exchange translation		3,250	4,099
Benefits paid		(55,332)	(54,483)
Lump-sum payments		(27,539)	(29,697)
Benefit obligations at end of fiscal year		1,287,692	1,377,739	1,437,843
Change in plan assets:
Fair value of plan assets at beginning of fiscal year		2,114,011	2,412,745
Actual return (negative return) on plan assets		92,893	(8,008)
Foreign exchange translation		3,158	3,863
Partial withdrawal of assets from employee retirement benefits trusts (Note)	[1]	(147,181)	(270,172)
Employer contributions		23,613	28,977
Plan participants' contributions		1,053	1,089
Benefits paid		(55,332)	(54,483)
Fair value of plan assets at end of fiscal year		2,032,215	2,114,011	¥ 2,412,745
Funded status		744,523	736,272
Amounts recognized in the consolidated balance sheets consist of:
Prepaid pension cost		768,998	762,147
Accrued pension liability		(24,475)	(25,875)
Net amount recognized		744,523	736,272
Amounts recognized in Accumulated other comprehensive income (loss) before-tax consist of:
Prior service benefits (cost)		58,173	63,030
Net actuarial gain (loss)		524,571	421,690
Net amount recognized		¥ 582,744	¥ 484,720
[1]During the fiscal year ended March 31, 2022 and 2023, certain subsidiaries of MHFG partially withdrew assets from employee retirement benefit trusts, which were established for the payment of employees’ severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2023. No gains or losses have been recognized as a result of this transaction.

Pension and Other Employee Be_8

Pension and Other Employee Benefit Plans (Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Gain (loss) recognized	¥ 0	¥ 0	¥ 3,945

Pension and Other Employee Be_9

Pension and Other Employee Benefit Plans (Plans with Projected Benefit Obligations in Excess of Plan Assets and Plans with Accumulated Benefit Obligations in Excess of Plan Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	[1]	¥ 29,389	¥ 31,829
Fair value of plan assets		4,914	5,954
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		29,389	31,829
Fair value of plan assets		¥ 4,914	¥ 5,954
[1]The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets.

Pension and Other Employee B_10

Pension and Other Employee Benefit Plans (Target Allocation for Plan Assets Excluding those of Employee Retirement Benefit Trusts) (Detail)	Mar. 31, 2023
Asset category
Plan assets	100%
General Account Assets
Asset category
Plan assets	10%	[1]
Other assets
Asset category
Plan assets	5%
Foreign | Equity securities
Asset category
Plan assets	26%
Foreign | Debt securities
Asset category
Plan assets	24%
Japan | Equity securities
Asset category
Plan assets	3%
Japan | Debt securities
Asset category
Plan assets	32%
[1]General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments.

Pension and Other Employee B_11

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022		Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 2,032,215	¥ 2,114,011		¥ 2,412,745
Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,018,000	1,003,000
Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		94,000	172,000
Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	8,000	7,000
Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	3,000	10,000
Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		187,000	179,000
Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		15,000	18,000
All Other | General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	113,000	116,000
All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		106,000	5,000
All Other | Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[3]	325,000	376,000
Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	1,018,000	1,003,000
Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	11,000	18,000
Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	8,000	10,000
Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		123,000	179,000
Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		21,000	21,000
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,514,000	1,567,000
Level 1 | Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		94,000	172,000
Level 1 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		173,000	170,000
Level 1 | All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		101,000	30,000	[5]
Level 1 | Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	1,018,000	1,003,000
Level 1 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	5,000	13,000
Level 1 | Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		123,000	179,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		193,000	171,000
Level 2 | Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	8,000	7,000
Level 2 | Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	3,000	10,000
Level 2 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		14,000	9,000
Level 2 | Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		15,000	18,000
Level 2 | All Other | General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	113,000	116,000
Level 2 | All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		5,000	(25,000)
Level 2 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	6,000	5,000
Level 2 | Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	8,000	10,000
Level 2 | Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 21,000	¥ 21,000
[1]These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request.[2]Investments in this class are measured at conversion value, which is equivalent to fair value.[3]In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.[4]This class represents equity securities held in the employee retirement benefit trusts of ¥1,003 billion and ¥1,018 billion carried at fair value at March 31, 2022 and 2023, respectively, which are well-diversified across industries.[5]Amounts primarily include cash and short-term assets carried at fair value.

Pension and Other Employee B_12

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		¥ 2,032,215	¥ 2,114,011	¥ 2,412,745
Equity securities | Common stocks
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		1,018,000	1,003,000
Equity securities | Common stocks | Japan
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts	[1]	¥ 1,018,000	¥ 1,003,000
[1]This class represents equity securities held in the employee retirement benefit trusts of ¥1,003 billion and ¥1,018 billion carried at fair value at March 31, 2022 and 2023, respectively, which are well-diversified across industries.

Pension and Other Employee B_13

Pension and Other Employee Benefit Plans (Forecasted Benefit Payments Including Effect of Expected Future Service) (Detail) ¥ in Millions	Mar. 31, 2023 JPY (¥)
Defined Benefit Plan Disclosure [Line Items]
2024	¥ 82,311
2025	75,506
2026	75,992
2027	74,496
2028	76,348
2029-2033	¥ 330,309

Derivative Financial Instrume_3

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2023	Mar. 31, 2022
Derivatives, Fair Value [Line Items]
Notional amount	[1]	¥ 2,279,203	¥ 1,635,837
Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	1,991,016	1,395,950
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	257,392	217,462
Equity-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	7,149	9,887
Credit-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	22,748	11,857
Other contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	898	681
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	12,932	9,723
Fair value of derivative payables	[2]	12,896	9,770
Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	8,374	4,624
Fair value of derivative payables	[2]	8,517	4,716
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	4,222	4,436
Fair value of derivative payables	[2]	4,013	4,472
Not Designated as Hedging Instrument | Equity-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	145	426
Fair value of derivative payables	[2]	197	345
Not Designated as Hedging Instrument | Credit-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	144	118
Fair value of derivative payables	[2]	126	121
Not Designated as Hedging Instrument | Other contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	47	119
Fair value of derivative payables	[2]	¥ 43	¥ 116
[1]Notional amount includes the sum of gross long and gross short third-party contracts.[2]Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively.

Derivative Financial Instrume_4

Derivative Financial Instruments - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Derivative [Line Items]
Cash collateral provided and not offset against derivative positions and included in Other assets	¥ 988,881	¥ 1,549,483
Cash collateral accepted and not offset against derivative positions and included in Other liabilities	1,008,083	1,075,591
Assets Needed for Immediate Settlement, Aggregate Fair Value	151,000	0
Mizuho Financial Group, Inc.
Derivative [Line Items]
Cash collateral provided and not offset against derivative positions and included in Other assets	¥ 989,000	¥ 1,549,000

Derivative Financial Instrume_5

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 399,073	¥ 737,778	¥ (157,122)
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		(508,743)	(130,312)	(27,893)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		317,459	145,979	115,181
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		534,615	728,226	(209,488)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	(3,857)	(13,877)	(58,602)
Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 59,599	¥ 7,762	¥ 23,680
[1]Amounts include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively.

Derivative Financial Instrume_6

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 399,073	¥ 737,778	¥ (157,122)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	(3,857)	(13,877)	(58,602)
Credit-related contracts | Loans related to credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (653)	¥ (605)	¥ (2,956)
[1]Amounts include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively.

Derivative Financial Instrume_7

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Credit Derivatives) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Credit protection written
Credit Derivatives [Line Items]
Notional amount	¥ 10,271	¥ 5,167
Fair value	93	92
Credit protection written | Investment grade
Credit Derivatives [Line Items]
Notional amount	4,497	3,045
Fair value	31	38
Credit protection written | Non-investment grade
Credit Derivatives [Line Items]
Notional amount	5,774	2,122
Fair value	62	54
Credit protection purchased
Credit Derivatives [Line Items]
Notional amount	12,477	6,690
Fair value	¥ (75)	¥ (95)

Derivative Financial Instrume_8

Derivative Financial Instruments (Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 10,271	¥ 5,167
One year or less
Credit Derivatives [Line Items]
Maximum payout/Notional amount	331	245
After one year through five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	9,585	4,785
After five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 355	¥ 137

Derivative Financial Instrume_9

Derivative Financial Instruments (Quantitative Information about Derivative Instruments with Credit-risk-related Contingent Features) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Credit Derivatives [Line Items]
Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions	¥ 814	¥ 1,149
Collateral provided to counterparties in the normal course of business	663	1,164
Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered	¥ 151	¥ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Commitments And Contingencies Disclosure [Line Items]
Carrying amount of guarantees and similar obligations	¥ 315,000	¥ 443,000
Carrying amounts of derivatives that are deemed to guarantees	285,000	416,000
Allowance for credit losses on off-balance-sheet instruments	6,581	(14,819)	¥ 18,007
Other Liabilities
Commitments And Contingencies Disclosure [Line Items]
Allowance for credit losses on off-balance-sheet instruments	¥ 78,000	¥ 71,000

Commitments and Contingencies_2

Commitments and Contingencies (Summary of Maximum Potential Amount of Future Payments under Guarantees) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 3,548	¥ 3,254
Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	228	419
Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	82	75
Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	3,306	2,899
Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	18	22
Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	554	478
Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	83,420	36,484
One year or less | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,954	2,084
One year or less | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	149	314
One year or less | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	14	9
One year or less | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	2,339	2,381
One year or less | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	0	0
One year or less | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	97	116
One year or less | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	53,774	17,110
After one year through five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,413	996
After one year through five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	26	42
After one year through five years | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	68	66
After one year through five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	869	451
After one year through five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	8	9
After one year through five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	282	199
After one year through five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	24,954	15,721
After five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	181	174
After five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	53	63
After five years | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	0	0
After five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	98	67
After five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	10	13
After five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	175	163
After five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 4,692	¥ 3,653

Commitments and Contingencies_3

Commitments and Contingencies (Summary of Maximum Potential Amount of Future Payments of Certain Guarantees Classified Based on Internal Ratings) (Detail) - Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees - JPY (¥) ¥ in Billions		Mar. 31, 2023	Mar. 31, 2022
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 7,164	¥ 6,647
Investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	[1]	5,587	5,336
Non-investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 1,577	¥ 1,311
[1]Investment grade in the internal rating scale generally corresponds to BBB- or above in the external rating scale.

Commitments and Contingencies_4

Commitments and Contingencies (Summary of Contractual Amounts with Regard to Undrawn Commitments) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2023	Mar. 31, 2022
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 102,309	¥ 93,625
Commitments to Extend Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments	[1]	100,973	92,203
Commercial letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 1,336	¥ 1,422
[1]Commitments to extend credit include commitments to invest in securities.

Commitments and contingencies_5

Commitments and contingencies - Schedule Of Balance Sheet Information Related to Operating Lease (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Right-of-use assets	[1]	¥ 549,668	¥ 570,171
Lease liabilities	[1]	¥ 571,087	¥ 593,339
Weighted average:
Remaining lease term		14 years 8 months 12 days	15 years 6 months
Discount rate		0.66%	0.60%
[1]Right-of-use assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.

Commitments and contingencies_6

Commitments and contingencies - Schedule Of Operating Lease Cost And Supplemental Cash Flow Information (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Lease cost	[1]	¥ 101,808	¥ 111,907	¥ 119,453
Right-of-use assets obtained in exchange for new lease liabilities		65,417	51,901	108,430
Operating cash flows		¥ 86,329	¥ 101,223	¥ 102,150
[1]Lease cost for operating leases are included in Occupancy expenses on the consolidated statements of income. The Group’s variable lease costs and costs for leases with terms of twelve months or less are not significant.

Commitments and contingencies_7

Commitments and contingencies - Schedule Of Future Lease Payments Under Operating Leases (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2024		¥ 79,207
2025		60,345
2026		53,518
2027		43,575
2028		34,048
2029 and thereafter		324,165
Total lease payments		594,858
Amount representing interest		23,771
Total lease liabilities for operating leases	[1]	¥ 571,087	¥ 593,339
[1]Right-of-use assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.

Variable Interest Entities an_3

Variable Interest Entities and Securitizations (Consolidated Assets of Consolidated VIEs as well as Total Assets and Maximum Exposure to Loss for Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Variable Interest Entity [Line Items]
Total assets of MHFG	¥ 248,780,722	¥ 231,550,704	¥ 221,651,500
Significant unconsolidated VIEs- Maximum exposure to loss	979,000	809,000
Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	12,153,544	11,574,978
Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	3,621,000	3,582,000
Asset-backed commercial paper/loan programs
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	0
Asset-backed commercial paper/loan programs | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	3,082,000	2,709,000
Asset-backed commercial paper/loan programs | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	0
Asset-backed securitizations
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	134,000	90,000
Asset-backed securitizations | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	1,514,000	1,363,000
Asset-backed securitizations | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	224,000	190,000
Investments in securitization products
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	0
Investments in securitization products | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	387,000	388,000
Investments in securitization products | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	0
Investment funds
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	845,000	719,000
Investment funds | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	2,294,000	1,816,000
Investment funds | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	3,397,000	3,392,000
Trust arrangements and other
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	0
Trust arrangements and other | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	4,877,000	¥ 5,299,000
Trust arrangements and other | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	¥ 0

Variable Interest Entities an_4

Variable Interest Entities and Securitizations (Carrying Amounts and Classification of Assets and Liabilities on Consolidated Balance Sheets that Relate to Variable Interests in Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Assets on consolidated balance sheets
Trading account assets		¥ 29,641,038	¥ 24,652,067
Loans		93,474,798	89,480,766
Total assets		248,780,722	231,550,704	¥ 221,651,500
Liabilities on the MHFG Group's balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		886,391	1,360,743
Trading account liabilities		19,362,943	14,859,383
Total liabilities		239,055,588	222,108,473
Maximum exposure to loss		979,000	809,000
Unconsolidated VIEs
Assets on consolidated balance sheets
Total assets		3,621,000	3,582,000
Mizuho Financial Group Inc | Unconsolidated VIEs
Assets on consolidated balance sheets
Trading account assets		83,000	143,000
Investments		482,000	430,000
Loans		154,000	92,000
Total assets		719,000	665,000
Liabilities on the MHFG Group's balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		0	54,000
Trading account liabilities		1,000	2,000
Total liabilities		1,000	56,000
Maximum exposure to loss	[1]	¥ 979,000	¥ 809,000
[1]This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet exposures and off-balance-sheet liabilities such as undrawn commitments.

Variable Interest Entities an_5

Variable Interest Entities and Securitizations - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Consolidated MHFG's balance sheets
Long-term debt	¥ 14,893,023	¥ 12,578,216
Noncontrolling interests	809,643	528,019
Unconsolidated VIEs
Consolidated MHFG's balance sheets
Noncontrolling interests	719,000	388,000
Debt Instrument [Member]
Consolidated MHFG's balance sheets
Long-term debt	¥ 200,000	¥ 367,000

Summary of Noninterest Income (

Summary of Noninterest Income (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 984,345	¥ 980,000	¥ 912,684
Foreign exchange gains (losses)—net	[1]	189,526	91,611	89,267
Trading account gains (losses)—net		(603,910)	(491,947)	120,596
Investment gains (losses)—net:
Debt securities		5,167	(14,777)	(22,032)
Equity securities		135,601	(60,563)	850,567
Equity in earnings (losses) of equity method investees—net	[2]	(26,999)	34,587	31,027
Gains on disposal of premises and equipment		4,920	9,943	7,125
Other noninterest income	[3],[4]	199,453	120,936	52,086
Total noninterest income		888,103	669,790	2,041,320
Premises and Equipment
Investment gains (losses)—net:
Gains on disposal of premises and equipment	[2]	4,920	9,943	7,125
Foreign Exchange
Disaggregation of Revenue [Line Items]
Foreign exchange gains (losses)—net	[2]	189,526	91,611	89,267
Trading Account Gains
Disaggregation of Revenue [Line Items]
Trading account gains (losses)—net	[3]	(603,910)	(491,947)	120,596
Debt securities
Investment gains (losses)—net:
Debt securities	[2]	5,167	(14,777)	(22,032)
Equity securities
Investment gains (losses)—net:
Equity securities	[2]	135,601	(60,563)	850,567
Securities related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	190,026	184,014	170,216
Deposits related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	15,540	15,358	15,162
Lending related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[3],[6]	193,838	162,953	158,921
Correspondent clearing
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	104,201	103,979	109,111
Investment advisory, management and administrative service
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	109,358	122,014	104,753
Fiduciary and trust
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	130,576	141,365	122,215
Agency business
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	36,529	36,899	31,331
Guarantee-related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[2]	41,150	35,296	31,665
Financial service, other
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	163,127	178,122	169,310
Financial service
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 984,345	¥ 980,000	¥ 912,684
[1]Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.[2]These amounts are revenues from contracts that do not meet the scope of ASC 606.[3]Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.[4]These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 26 “Fair value” for further details.[5]These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers” (“ASC 606”).[6]Most of the lending-related fees such as commitment fees and arrangement fees are not within the scope of ASC 606.

Noninterest Income - Additional

Noninterest Income - Additional Information (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Other Revenues [Line Items]
Trust fees		¥ 55,000	¥ 56,000	¥ 51,000
Fees related to trust business		76,000	85,000	71,000
Trading account gains (losses)—net		(603,910)	(491,947)	120,596
Other noninterest income	[1],[2]	199,453	120,936	52,086
Revenue from contracts with customers ("ASC 606")
Other Revenues [Line Items]
Trading account gains (losses)—net		59,000	83,000	86,000
Other noninterest income		¥ 21,000	¥ 15,000	¥ 15,000
[1]Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.[2]These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 26 “Fair value” for further details.

Trading Account Gains and Los_3

Trading Account Gains and Losses (Net Trading Gains and Losses) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		¥ (603,910)	¥ (491,947)	¥ 120,596
Foreign exchange gains (losses)—net	[1]	189,526	91,611	89,267
Net trading gains (losses)		(414,384)	(400,336)	209,863
Interest rate contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		(508,743)	(130,312)	(27,893)
Foreign exchange contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[2]	317,459	145,979	115,181
Equity-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		534,615	728,226	(209,488)
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[3]	(3,204)	(13,272)	(55,646)
Other contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		59,599	7,762	23,680
Trading securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		¥ (1,003,636)	¥ (1,230,330)	¥ 274,762
[1]Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.[2]Amounts include gains and losses on currency swaps.[3]Amounts do not include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively. The net gains (losses) is recorded in Other noninterest income (expenses).

Trading Account Gains and Los_4

Trading Account Gains and Losses (Net Trading Gains and Losses) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ 399,073	¥ 737,778	¥ (157,122)
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income	[1]	(3,857)	(13,877)	(58,602)
Credit-related contracts | Loans related to credit derivatives
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ (653)	¥ (605)	¥ (2,956)
[1]Amounts include the net gains (losses) of ¥(2,956) million, ¥(605) million and ¥(653) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2021, 2022 and 2023, respectively.

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - JPY (¥)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Carrying amounts of other equity interests of which fair value is not readily determinable	¥ 208,000,000,000	¥ 207,000,000,000
Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale	0	97
Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale	99.6	100
Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale	77.6	99
Senior borrowings and bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
The differences between the aggregate fair value and aggregate unpaid principal balance of the notes for which the fair value option has been elected	161,000,000,000	90,000,000,000
Net unrealized gains (losses) resulting from changes in fair values of the notes	¥ 54,000,000,000	38,000,000,000	¥ (10,000,000,000)
Investment funds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Underlying assets, estimated remaining liquidation period	10 years
Long-term debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of liabilities transferred into Level 3	¥ 1,000,000,000	4,000,000,000
Fair value of liabilities transferred out of Level 3	2,000,000,000	6,000,000,000
Trading securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of assets transferred into Level 3	13,000,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	15,000,000,000	452,000,000,000
Available-for-sale securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	54,000,000,000
Fair value of liabilities transferred out of Level 3		693,000,000,000
Available-for-sale securities | Non Japanese Corporate Bonds [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	54,000,000,000	¥ 4,000,000,000
Other Investments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	¥ 1,000,000,000

Fair Value (Summary of Assets a

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Assets:
Available-for-sale securities		¥ 23,233,769	¥ 31,673,890
Liabilities:
Long-term debt		2,680,164	2,756,062
Fair Value, Measurements, Recurring
Assets:
Equity securities with readily determinable fair values		3,213,000	3,155,000
Equity securities measured at net asset value	[1]	271,000	210,000
Securities measured at net asset value	[1],[2]	111,000	284,000
Other investments		63,000	58,000
Total assets measured at fair value		56,422,000	59,749,000
Liabilities:
Trading securities sold, not yet purchased		6,467,000	5,089,000
Long-term debt	[3]	2,680,000	2,756,000
Total liabilities measured at fair value		22,043,000	17,615,000
Fair Value, Measurements, Recurring | Interest rate contracts
Assets:
Assets, derivatives		8,374,000	4,624,000
Liabilities:
Liabilities, derivatives		8,517,000	4,716,000
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets:
Assets, derivatives		4,222,000	4,436,000
Liabilities:
Liabilities, derivatives		4,013,000	4,472,000
Fair Value, Measurements, Recurring | Equity-related contracts
Assets:
Assets, derivatives		145,000	426,000
Liabilities:
Liabilities, derivatives		197,000	345,000
Fair Value, Measurements, Recurring | Credit-related contracts
Assets:
Assets, derivatives		144,000	118,000
Liabilities:
Liabilities, derivatives		126,000	121,000
Fair Value, Measurements, Recurring | Other contracts
Assets:
Assets, derivatives		47,000	119,000
Liabilities:
Liabilities, derivatives		43,000	116,000
Fair Value, Measurements, Recurring | Japanese government bonds
Assets:
Assets, trading securities	[2]	1,194,000	1,615,000
Available-for-sale securities		16,449,000	25,159,000
Fair Value, Measurements, Recurring | Japanese local government bonds
Assets:
Assets, trading securities	[2]	138,000	145,000
Available-for-sale securities		555,000	420,000
Fair Value, Measurements, Recurring | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[2]	3,294,000	3,064,000
Available-for-sale securities		376,000	373,000
Fair Value, Measurements, Recurring | Other foreign government bonds
Assets:
Assets, trading securities	[2]	1,444,000	1,546,000
Available-for-sale securities		1,308,000	1,336,000
Fair Value, Measurements, Recurring | Agency mortgage-backed securities
Assets:
Assets, trading securities	[2]	5,309,000	3,176,000
Available-for-sale securities		522,000	451,000
Fair Value, Measurements, Recurring | Residential mortgage-backed securities
Assets:
Assets, trading securities	[2]	0	8,000
Available-for-sale securities		47,000	58,000
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		862,000	854,000
Fair Value, Measurements, Recurring | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[2]	516,000	640,000
Fair Value, Measurements, Recurring | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[2],[4]	2,453,000	2,829,000
Fair Value, Measurements, Recurring | Equity securities
Assets:
Assets, trading securities	[2]	2,250,000	1,622,000
Fair Value, Measurements, Recurring | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		2,109,000	2,235,000
Fair Value, Measurements, Recurring | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,006,000	788,000
Fair Value, Measurements, Recurring | Level 1
Assets:
Equity securities with readily determinable fair values		3,052,000	3,094,000
Other investments		0	2,000
Total assets measured at fair value		25,414,000	34,969,000
Liabilities:
Trading securities sold, not yet purchased		2,954,000	3,054,000
Total liabilities measured at fair value		3,254,000	3,284,000
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Assets:
Assets, derivatives		218,000	89,000
Liabilities:
Liabilities, derivatives		244,000	80,000
Fair Value, Measurements, Recurring | Level 1 | Equity-related contracts
Assets:
Assets, derivatives		39,000	77,000
Liabilities:
Liabilities, derivatives		46,000	122,000
Fair Value, Measurements, Recurring | Level 1 | Other contracts
Assets:
Assets, derivatives		15,000	49,000
Liabilities:
Liabilities, derivatives		10,000	28,000
Fair Value, Measurements, Recurring | Level 1 | Japanese government bonds
Assets:
Assets, trading securities	[2]	1,187,000	1,604,000
Available-for-sale securities		15,771,000	24,662,000
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[2]	1,917,000	2,353,000
Available-for-sale securities		376,000	373,000
Fair Value, Measurements, Recurring | Level 1 | Other foreign government bonds
Assets:
Assets, trading securities	[2]	658,000	907,000
Available-for-sale securities		322,000	363,000
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[2],[4]	0	15,000
Fair Value, Measurements, Recurring | Level 1 | Equity securities
Assets:
Assets, trading securities	[2]	1,859,000	1,381,000
Fair Value, Measurements, Recurring | Level 2
Assets:
Equity securities with readily determinable fair values		161,000	61,000
Total assets measured at fair value		30,162,000	23,539,000
Liabilities:
Trading securities sold, not yet purchased		3,513,000	2,035,000
Long-term debt	[3]	1,844,000	1,962,000
Total liabilities measured at fair value		17,863,000	13,444,000
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Assets:
Assets, derivatives		8,103,000	4,513,000
Liabilities:
Liabilities, derivatives		8,271,000	4,636,000
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets:
Assets, derivatives		4,200,000	4,404,000
Liabilities:
Liabilities, derivatives		4,005,000	4,472,000
Fair Value, Measurements, Recurring | Level 2 | Equity-related contracts
Assets:
Assets, derivatives		73,000	323,000
Liabilities:
Liabilities, derivatives		91,000	183,000
Fair Value, Measurements, Recurring | Level 2 | Credit-related contracts
Assets:
Assets, derivatives		143,000	116,000
Liabilities:
Liabilities, derivatives		124,000	120,000
Fair Value, Measurements, Recurring | Level 2 | Other contracts
Assets:
Assets, derivatives		12,000	18,000
Liabilities:
Liabilities, derivatives		15,000	36,000
Fair Value, Measurements, Recurring | Level 2 | Japanese government bonds
Assets:
Assets, trading securities	[2]	7,000	11,000
Available-for-sale securities		678,000	497,000
Fair Value, Measurements, Recurring | Level 2 | Japanese local government bonds
Assets:
Assets, trading securities	[2]	138,000	145,000
Available-for-sale securities		555,000	420,000
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[2]	1,377,000	711,000
Fair Value, Measurements, Recurring | Level 2 | Other foreign government bonds
Assets:
Assets, trading securities	[2]	786,000	639,000
Available-for-sale securities		986,000	973,000
Fair Value, Measurements, Recurring | Level 2 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[2]	5,309,000	3,176,000
Available-for-sale securities		522,000	451,000
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities		34,000	40,000
Fair Value, Measurements, Recurring | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		862,000	854,000
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[2]	516,000	640,000
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[2],[4]	2,406,000	2,743,000
Fair Value, Measurements, Recurring | Level 2 | Equity securities
Assets:
Assets, trading securities	[2]	370,000	213,000
Fair Value, Measurements, Recurring | Level 2 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		2,008,000	1,920,000
Fair Value, Measurements, Recurring | Level 2 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		916,000	671,000
Fair Value, Measurements, Recurring | Level 3
Assets:
Other investments		63,000	56,000
Total assets measured at fair value		464,000	747,000
Liabilities:
Long-term debt	[3]	836,000	794,000
Total liabilities measured at fair value		926,000	887,000
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Assets:
Assets, derivatives		53,000	22,000
Liabilities:
Liabilities, derivatives		2,000
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets:
Assets, derivatives		22,000	32,000
Liabilities:
Liabilities, derivatives		8,000
Fair Value, Measurements, Recurring | Level 3 | Equity-related contracts
Assets:
Assets, derivatives		33,000	26,000
Liabilities:
Liabilities, derivatives		60,000	40,000
Fair Value, Measurements, Recurring | Level 3 | Credit-related contracts
Assets:
Assets, derivatives		1,000	2,000
Liabilities:
Liabilities, derivatives		2,000	1,000
Fair Value, Measurements, Recurring | Level 3 | Other contracts
Assets:
Assets, derivatives		20,000	52,000
Liabilities:
Liabilities, derivatives		18,000	52,000
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[2]	0	8,000
Available-for-sale securities		13,000	18,000
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[2],[4]	47,000	71,000
Fair Value, Measurements, Recurring | Level 3 | Equity securities
Assets:
Assets, trading securities	[2]	21,000	28,000
Fair Value, Measurements, Recurring | Level 3 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		101,000	315,000
Fair Value, Measurements, Recurring | Level 3 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		¥ 90,000	¥ 117,000
[1]In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2022 and 2023 were ¥68 billion and ¥52 billion, respectively.[2]Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option.[3]Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception.[4]The amount includes CLO and convertible bonds, which are classified in Level 3.

Fair Value (Summary of Assets_2

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unfunded commitments	¥ 52	¥ 68

Fair Value (Reconciliation for

Fair Value (Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Trading securities sold, not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Purchases		¥ (1)
Sales		1
Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		794	¥ 713
Gains (losses) in Earnings	[1]	29	61
Gains (losses) in OCI	[2]	10	1
Transfers into Level 3		1	4
Transfers out of level 3		(2)	(6)
Issuances		323	534
Settlements		(241)	(389)
Ending Balance		836	794
Change in unrealized gain (losses) still held	[3]	60	77
Trading securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3		13
Transfers out of level 3		(15)	(452)
Trading securities | Residential mortgage- backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		8	9
Gains (losses) in Earnings	[4]	(1)
Sales		(6)
Settlements		(1)	(1)
Ending Balance			8
Trading securities | Corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		71	1,033
Gains (losses) in Earnings	[4]	4	7
Transfers into Level 3		13
Transfers out of level 3		(15)	(452)
Purchases		104	143
Sales		(46)	(72)
Settlements		(84)	(588)
Ending Balance		47	71
Change in unrealized gain (losses) still held	[3]		3
Trading securities | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		28	29
Purchases		2
Sales		(6)
Settlements		(3)	(1)
Ending Balance		21	28
Change in unrealized gain (losses) still held	[3]	(1)	1
Derivative financial instruments assets | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	22	8
Gains (losses) in Earnings	[4],[5]	31	11
Settlements	[5]	(2)	3
Ending Balance	[5]	51	22
Change in unrealized gain (losses) still held	[3],[5]	(22)	(22)
Derivative financial instruments assets | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	32	23
Gains (losses) in Earnings	[4],[5]	(5)	8
Settlements	[5]	(13)	1
Ending Balance	[5]	14	32
Change in unrealized gain (losses) still held	[3],[5]	(6)	7
Derivative financial instruments assets | Equity-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	(14)	(21)
Gains (losses) in Earnings	[4],[5]	(26)	(11)
Settlements	[5]	13	18
Ending Balance	[5]	(27)	(14)
Change in unrealized gain (losses) still held	[3],[5]	(107)	(23)
Derivative financial instruments assets | Credit-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	1	2
Gains (losses) in Earnings	[4],[5]	(1)	(3)
Settlements	[5]	(1)	2
Ending Balance	[5]	(1)	1
Change in unrealized gain (losses) still held	[3],[5]	(5)	(1)
Derivative financial instruments assets | Other contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gains (losses) in Earnings	[4],[5]	2	1
Settlements	[5]		(1)
Ending Balance	[5]	2
Change in unrealized gain (losses) still held	[3],[5]	2
Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of level 3		(54)
Transfers out of level 3			(693)
Available-for-sale securities | Residential mortgage- backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		18	23
Settlements		(5)	(5)
Ending Balance		13	18
Available-for-sale securities | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			716
Gains (losses) in Earnings	[6]		5
Gains (losses) in OCI	[2]		(5)
Transfers out of level 3			(689)
Purchases			62
Sales			(60)
Settlements			(29)
Available-for-sale securities | Japanese corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		315	365
Gains (losses) in Earnings	[6]		(20)
Gains (losses) in OCI	[2]	3	1
Transfers out of level 3			(4)
Purchases		25	11
Settlements		(242)	(38)
Ending Balance		101	315
Change in unrealized gain (losses) still held	[3]	8	(19)
Available-for-sale securities | Foreign corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		117	132
Gains (losses) in OCI	[2]	1	7
Transfers out of level 3		(54)	(4)
Purchases		63	47
Settlements		(37)	(65)
Ending Balance		90	117
Change in unrealized gain (losses) still held	[3]		1
Available-for-sale securities | Other investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		56	53
Gains (losses) in Earnings	[6]	3	2
Transfers out of level 3		(1)
Purchases		36	37
Sales			(3)
Settlements		(31)	(33)
Ending Balance		63	56
Change in unrealized gain (losses) still held	[3]	¥ 1	¥ (2)
[1]Gains (losses) in Earnings are reported in Other noninterest income (expenses).[2]Gains (losses) in OCI are reported in Other comprehensive income (loss).[3]Amounts represent total gains or losses recognized in earnings and other comprehensive income (loss) during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2022 and 2023. The amounts of unrealized gains (losses) in other comprehensive income (loss) are related to Available-for-sale securities and Long-term debt, which were ¥2 billion and ¥2 billion, respectively, at March 31, 2022, and ¥8 billion and ¥11 billion, respectively, at March 31, 2023.[4]Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses).[5]Total Level 3 derivative exposures have been netted on the table for presentation purposes only.[6]Gains (losses) in Earnings are reported in Investment gains (losses)—net.

Fair Value (Reconciliation fo_2

Fair Value (Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Unrealized gains (losses) in OCI related to Available-for-sale securities	¥ 8	¥ 2
Unrealized gains (losses) in OCI related to Long-term debt	¥ 11	¥ 2

Fair Value (Quantitative Inform

Fair Value (Quantitative Information about Significant Unobservable Inputs Related to Material Classes of Level 3 Assets and Liabilities) (Detail) ¥ in Millions		Mar. 31, 2023 JPY (¥)	Mar. 31, 2022 JPY (¥)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		¥ 2,680,164	¥ 2,756,062
Trading securities and Available-for- sale | Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		13,000	26,000
Trading securities and Available-for- sale | Corporate bonds and other debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		238,000	503,000
Derivative Financial Instruments | Other contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		2,000	0
Derivative Financial Instruments | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		51,000	22,000
Derivative Financial Instruments | Foreign exchange contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		14,000	32,000
Derivative Financial Instruments | Equity-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		(27,000)	(14,000)
Derivative Financial Instruments | Credit-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		(1,000)	1,000
Long-term debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		¥ 836,000	¥ 794,000
Minimum | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0.2	0.4
Minimum | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	21.7	5.8
Minimum | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0	0
Minimum | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	0.2	0.2
Minimum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	0.1	0.1
Minimum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	0.1	0.1
Minimum | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100	100
Minimum | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	40.5	10
Minimum | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0.0030	0.0030
Minimum | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	0.00988	0.00354
Minimum | Measurement Input, Discount Rate1 [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[3]	0.00035	0.00039
Minimum | Measurement Input, IR - IR correlation [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	23.2	23.2
Minimum | Measurement Input, IR - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	23.2	23.2
Minimum | Measurement Input, FX - IR correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	5.5	11.4
Minimum | Measurement Input, FX - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	5.5	11.4
Minimum | Measurement Input, FX - FX correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	39	41.4
Minimum | Measurement Input, FX - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	39	41.4
Minimum | Measurement Input, Equity - IR correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	25	25
Minimum | Measurement Input, Equity - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	25	25
Minimum | Measurement Input, Equity - FX correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	0
Minimum | Measurement Input, Equity - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	(16.3)	(16.9)
Minimum | Measurement Input, Equity volatility [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		10.3	12.6	[2]
Minimum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	5.9	8.7
Minimum | Measurement Input, Credit correlation [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]		42.6
Minimum | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	47.6	18.6
Minimum | Measurement Input, Equity correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	73.9	3.2
Minimum | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	3.2	3.2
Minimum | Measurement Input Commodity Volatility [Member] | Derivative Financial Instruments | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	20	0
Maximum | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		17.6	18.1
Maximum | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	21.7	24.5
Maximum | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		2.2	0.5
Maximum | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	0.2	59.7
Maximum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	12.2	8
Maximum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	13.1	8
Maximum | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100	100
Maximum | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	40.5	39.7
Maximum | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0.01671	0.01671
Maximum | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	0.02099	0.01025
Maximum | Measurement Input, Discount Rate1 [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[3]	0.01712	0.04466
Maximum | Measurement Input, IR - IR correlation [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	100	100
Maximum | Measurement Input, IR - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	100	100
Maximum | Measurement Input, FX - IR correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	58.2	52.3
Maximum | Measurement Input, FX - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	58.2	52.3
Maximum | Measurement Input, FX - FX correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	64.7	64.8
Maximum | Measurement Input, FX - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	64.7	64.8
Maximum | Measurement Input, Equity - IR correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	25	25
Maximum | Measurement Input, Equity - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	25	25
Maximum | Measurement Input, Equity - FX correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	60
Maximum | Measurement Input, Equity - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	93.3	16.8
Maximum | Measurement Input, Equity volatility [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		95.4	120.5	[2]
Maximum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	180.8	120.5
Maximum | Measurement Input, Credit correlation [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]		100
Maximum | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	100	100
Maximum | Measurement Input, Equity correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	100	100
Maximum | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2]	100	100
Maximum | Measurement Input Commodity Volatility [Member] | Derivative Financial Instruments | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	54.5	89.4
Weighted Average | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	4.4	5.8
Weighted Average | Measurement Input, Prepayment Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1],[4]	21.7	24.3
Weighted Average | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	0.2	0
Weighted Average | Measurement Input, Default Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1],[4]	0.2	0.7
Weighted Average | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	2.1	1.5
Weighted Average | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	2.3	1.5
Weighted Average | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	100	100
Weighted Average | Measurement Input Recovery Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1],[4]	40.5	39.5
Weighted Average | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	0.0047	0.00531
Weighted Average | Measurement Input, Discount Rate [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1],[4]	0.01162	0.00471
Weighted Average | Measurement Input, Discount Rate1 [Member] | Trading securities and Available-for- sale | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[3],[4]	0.00201	0.03404
Weighted Average | Measurement Input, IR - IR correlation [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	75	75
Weighted Average | Measurement Input, IR - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	75	75
Weighted Average | Measurement Input, FX - IR correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	39.9	31.4
Weighted Average | Measurement Input, FX - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	39.9	38.9
Weighted Average | Measurement Input, FX - FX correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	51.9	53.1
Weighted Average | Measurement Input, FX - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	51.9	53.1
Weighted Average | Measurement Input, Equity - IR correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	25	25
Weighted Average | Measurement Input, Equity - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	25	25
Weighted Average | Measurement Input, Equity - FX correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	33.7
Weighted Average | Measurement Input, Equity - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	0	0
Weighted Average | Measurement Input, Equity volatility [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		44.1	47.3	[2],[4]
Weighted Average | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	34.1	34
Weighted Average | Measurement Input, Credit correlation [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]		66.2
Weighted Average | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	68.3	63.9
Weighted Average | Measurement Input, Equity correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	96.7	89.9
Weighted Average | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[2],[4]	90.8	89.6
Weighted Average | Measurement Input Commodity Volatility [Member] | Derivative Financial Instruments | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[4]	39.8	55.4
[1]These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS.[2]Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model.[3]This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds.[4]Averages are calculated by weighting each input by the relative fair value of the respective financial instruments except for derivative related inputs where medians are used.

Fair Value (Summary of Assets_3

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Assets:
Equity securities (without readily determinable fair values)	¥ 207,743	¥ 207,407	¥ 186,146
Fair Value, Measurements, Nonrecurring
Assets:
Loans	97,000	81,000
Loans held-for-sale	216,000	76,000
Equity securities (without readily determinable fair values)	4,000	4,000
Other investments	94,000
Premises and equipment—net	1,000
Total assets measured at fair value	412,000	161,000
Fair Value, Measurements, Nonrecurring | Aggregate cost
Assets:
Loans	165,000	128,000
Loans held-for-sale	282,000	77,000
Equity securities (without readily determinable fair values)	5,000	4,000
Other investments	122,000
Premises and equipment—net	2,000	13,000
Other assets		3,000
Total assets measured at fair value	576,000	225,000
Fair Value, Measurements, Nonrecurring | Level 1
Assets:
Other investments	93,000
Total assets measured at fair value	93,000
Fair Value, Measurements, Nonrecurring | Level 2
Assets:
Loans held-for-sale	16,000	27,000
Equity securities (without readily determinable fair values)	4,000	3,000
Total assets measured at fair value	20,000	30,000
Fair Value, Measurements, Nonrecurring | Level 3
Assets:
Loans	97,000	81,000
Loans held-for-sale	200,000	49,000
Equity securities (without readily determinable fair values)		1,000
Other investments	1,000
Premises and equipment—net	1,000
Total assets measured at fair value	¥ 299,000	¥ 131,000

Fair Value (Carrying Amounts an

Fair Value (Carrying Amounts and Fair Values of Certain Financial Instruments, Excluding Financial Instruments Carried at Fair Value on a Recurring Basis and Those outside Scope of ASC 825) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2023	Mar. 31, 2022
Financial liabilities:
Long-term debt		¥ 2,680,164	¥ 2,756,062
Carrying amount
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		83,226,000	68,366,000
Investments		2,050,000	1,519,000
Loans, net of allowance	[1]	93,291,000	89,264,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		64,618,000	58,054,000
Interest-bearing deposits		128,756,000	121,833,000
Due to trust accounts		749,000	390,000
Other short-term borrowings		3,397,000	7,567,000
Long-term debt		12,246,000	9,849,000
Estimated fair value
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		83,226,000	68,366,000
Investments		1,915,000	1,466,000
Loans, net of allowance	[1]	94,605,000	90,576,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		64,618,000	58,054,000
Interest-bearing deposits		128,718,000	121,807,000
Due to trust accounts		749,000	390,000
Other short-term borrowings		3,397,000	7,567,000
Long-term debt		11,719,000	9,681,000
Estimated fair value | Level 1
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		66,498,000	50,628,000
Investments		800,000	485,000
Estimated fair value | Level 2
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		16,728,000	17,738,000
Investments		1,115,000	981,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		64,618,000	58,054,000
Interest-bearing deposits		128,718,000	121,807,000
Due to trust accounts		749,000	390,000
Other short-term borrowings		3,397,000	7,567,000
Long-term debt		10,315,000	8,162,000
Estimated fair value | Level 3
Financial assets:
Loans, net of allowance	[1]	94,605,000	90,576,000
Financial liabilities:
Long-term debt		¥ 1,404,000	¥ 1,519,000
[1]Loans, net of allowance include items measured at fair value on a nonrecurring basis.

Offsetting of Financial Asset_3

Offsetting of Financial Assets and Financial Liabilities (Information of Offsetting of Financial Assets and Financial Liabilities) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2023	Mar. 31, 2022
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets, Gross amounts recognized	[1]	¥ 12,932	¥ 9,723
Derivative assets, Gross amounts offset on the balance sheet	[1]	0	0
Derivative assets, Net amounts presented on the balance sheet	[1],[2],[3]	12,932	9,723
Derivative assets, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(10,476)	(7,232)
Derivative assets, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	(821)	(891)
Derivative assets, Net amounts	[1]	1,635	1,600
Receivables under resale agreements, Gross amounts recognized	[1]	11,695	12,751
Receivables under resale agreements, Gross amounts offset on the balance sheet	[1]	0	0
Receivables under resale agreements, Net amounts presented on the balance sheet	[1],[2],[6]	11,695	12,751
Receivables under resale agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(10,565)	(11,437)
Receivables under resale agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Receivables under resale agreements, Net amounts	[1]	1,130	1,314
Receivables under securities borrowing transactions, Gross amounts recognized	[1]	1,892	2,339
Receivables under securities borrowing transactions, Gross amounts offset on the balance sheet	[1]	0	0
Receivables under securities borrowing transactions, Net amounts presented on the balance sheet	[1],[2],[7]	1,892	2,339
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(1,866)	(2,299)
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Receivables under securities borrowing transactions, Net amounts	[1]	26	40
Financial assets, Gross amounts recognized, Total	[1]	26,519	24,813
Financial assets, Gross amounts offset on the balance sheet, Total	[1]	0	0
Financial assets, Net amounts presented on the balance sheet, Total	[1],[2]	26,519	24,813
Financial assets, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[4],[5]	(22,907)	(20,968)
Financial assets, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[4]	(821)	(891)
Financial assets, Net amounts, Total	[1]	2,791	2,954
Derivative liabilities, Gross amounts recognized	[1]	12,896	9,770
Derivative liabilities, Gross amounts offset on the balance sheet	[1]	0	0
Derivative liabilities, Net amounts presented on the balance sheet	[1],[2],[3]	12,896	9,770
Derivative liabilities, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(10,141)	(6,716)
Derivative liabilities, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	(843)	(1,329)
Derivative liabilities, Net amounts	[1]	1,912	1,725
Payables under repurchase agreements, Gross amounts recognized	[1]	25,737	20,070
Payables under repurchase agreements, Gross amounts offset on the balance sheet	[1]	0	0
Payables under repurchase agreements, Net amounts presented on the balance sheet	[1],[2],[6]	25,737	20,070
Payables under repurchase agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(25,113)	(19,366)
Payables under repurchase agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Payables under repurchase agreements, Net amounts	[1]	624	704
Payables under securities lending transactions, Gross amounts recognized	[1]	886	1,361
Payables under securities lending transactions, Gross amounts offset on the balance sheet	[1]	0	0
Payables under securities lending transactions, Net amounts presented on the balance sheet	[1],[2],[7]	886	1,361
Payables under securities lending transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(755)	(1,164)
Payables under securities lending transactions, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Payables under securities lending transactions, Net amounts	[1]	131	197
Financial liabilities, Gross amounts recognized, Total	[1]	39,519	31,201
Financial liabilities, Gross amounts offset on the balance sheet, Total	[1]	0	0
Financial liabilities, Net amounts presented on the balance sheet, Total	[1],[2]	39,519	31,201
Financial liabilities, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[4],[5]	(36,009)	(27,246)
Financial liabilities, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[4]	(843)	(1,329)
Financial liabilities, Net amounts, Total	[1]	¥ 2,667	¥ 2,626
[1]Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off or where uncertainty exists as to the enforceability of these agreements are excluded. For derivatives, the table includes amounts relating to over-the-counter (“OTC”) and OTC-cleared derivatives that are subject to enforceable master netting arrangements or similar agreements.[2]Derivative assets and liabilities are recorded in Trading account assets and Trading account liabilities, respectively.[3]The amounts of derivative assets and liabilities subject to enforceable master netting arrangements or similar agreements were ¥9,326 billion and ¥9,235 billion, respectively, at March 31, 2022, and ¥12,574 billion and ¥12,432 billion, respectively, at March 31, 2023.[4]Amounts do not exceed the net amounts presented on the balance sheet and do not include the effect of overcollateralization, where it exists.[5]For derivatives, amounts include derivative assets or liabilities and securities collateral that are eligible for offsetting under enforceable master netting arrangements or similar agreements.[6]The amounts of Receivables under resale agreements and Payables under repurchase agreements subject to enforceable industry standard master repurchase agreements with netting terms were ¥11,537 billion and ¥19,505 billion, respectively, at March 31, 2022, and ¥10,587 billion and ¥25,147 billion, respectively, at March 31, 2023.[7]The amounts of Receivables under securities borrowing transactions and Payables under securities lending transactions subject to enforceable industry standard master lending agreements with netting terms were ¥2,339 billion and ¥1,172 billion, respectively, at March 31, 2022, and ¥1,892 billion and ¥758 billion, respectively, at March 31, 2023.

Offsetting of Financial Asset_4

Offsetting of Financial Assets and Financial Liabilities (Information of Offsetting of Financial Assets and Financial Liabilities) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Offsetting Financial Assets And Financial Liabilities [Line Items]
Receivables under resale agreement subject to enforceable master netting arrangements	¥ 10,587	¥ 11,537
Payables under repurchase agreement subject to enforceable master netting arrangements	25,147	19,505
Receivables under securities transaction borrowing subject to master netting arrangement	1,892	2,339
Payables under securities transaction lending subject to master netting arragement	758	1,172
Subject To Enforceable Master Netting Arragement [Member]
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets subject to enforceable master netting arrangements	12,574	9,326
Derivative liabilities subject to enforceable master netting arrangements	¥ 12,432	¥ 9,235

Repurchase Agreements and Sec_3

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities by Remaining Contractual Maturity) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	¥ 25,737	¥ 20,070
Securities lending transactions	886	1,361
Total	26,623	21,431
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	2,285	7,011
Securities lending transactions	685	1,098
Total	2,970	8,109
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	16,508	10,621
Securities lending transactions	73	74
Total	16,581	10,695
31 to 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	5,471	1,340
Securities lending transactions	0	0
Total	5,471	1,340
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	1,473	1,098
Securities lending transactions	128	189
Total	¥ 1,601	¥ 1,287

Repurchase Agreements and Sec_4

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities by Class of Underlying Collateral) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2023	Mar. 31, 2022
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	¥ 25,737	¥ 20,070
Securities lending transactions	886	1,361
Japanese government bonds and Japanese local government bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	6,114	1,714
Securities lending transactions	102	217
Foreign government bonds and foreign agency mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	17,475	17,445
Securities lending transactions	73	90
Commercial Paper and Corporate Bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	430	271
Securities lending transactions	0	52
Equity Securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	1,491	609
Securities lending transactions	711	989
Other
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	227	31
Securities lending transactions	¥ 0	¥ 13

Related Party Transactions - Su

Related Party Transactions - Summary of financial information of groups equity method investees (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
Loans	¥ 94,175,757	¥ 90,290,583
Total assets	248,780,722	231,550,704	¥ 221,651,500
Total liabilities	239,055,588	222,108,473
Total equity	9,725,134	9,442,231	9,688,157
Noncontrolling interests	809,643	528,019
Total interest and dividend income	3,388,791	1,443,941	1,456,556
Total interest expense	2,180,064	374,132	467,939
Provision (credit) for credit losses	93,753	214,408	112,776
Net interest income after provision (credit) for credit losses	1,114,974	855,401	875,841
Income before income tax expense	69,200	(242,500)	1,028,800
Net income	34,028	(101,471)	818,048
Equity Method Investee
Related Party Transaction [Line Items]
Loans	6,037,000	7,765,000
Total assets	29,367,000	30,180,000
Deposits	6,216,000	8,713,000
Total liabilities	26,506,000	27,474,000
Total equity	2,861,000	2,706,000
Noncontrolling interests	16,000	14,000
Total interest and dividend income	750,000	625,000	570,000
Total interest expense	239,000	182,000	188,000
Provision (credit) for credit losses	96,000	104,000	91,000
Net interest income after provision (credit) for credit losses	415,000	339,000	291,000
Income before income tax expense	261,000	332,000	237,000
Net income	¥ 194,000	¥ 246,000	¥ 178,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) ¥ in Billions	12 Months Ended
	Mar. 31, 2023 JPY (¥) Loans	Mar. 31, 2022 JPY (¥) Loans
Related Party Transaction [Line Items]
Number of loans impaired | Loans	0	0
Related party loan | ¥	¥ 732	¥ 604

Business Segment Information -

Business Segment Information - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2023 Segment
Segment Reporting Information [Line Items]
Number of operating segments	5

Business Segment Information (R

Business Segment Information (Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	¥ 2,280.2	¥ 2,254.5	¥ 2,200.8
General and administrative expenses	[1],[3]	1,473.6	1,415	1,408.7
Equity in earnings (losses) of equity method investees—net	[1]	11.9	25.4	19.9
Amortization of goodwill and others	[1]	11.4	11.7	12.2
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	807.1	853.2	799.8
Fixed assets	[1],[5]	1,678.6	1,697.3	1,755.7
Operating Segments | Retail And Business Banking Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	704	715	699.4
General and administrative expenses	[1],[3]	611.6	623.7	642.5
Equity in earnings (losses) of equity method investees—net	[1]	(17)	5.9	5.4
Amortization of goodwill and others	[1]	2.1	2.2	2.3
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	73.3	95	60
Fixed assets	[1],[5]	489.3	493	532.8
Operating Segments | Corporate And Institutional Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	502.3	494.4	475.5
General and administrative expenses	[1],[3]	197.3	201.4	209.8
Equity in earnings (losses) of equity method investees—net	[1]	6.4	3.8	3.9
Amortization of goodwill and others	[1]	0.1	0.1	0.1
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	311.3	296.7	269.5
Fixed assets	[1],[5]	150.1	159.1	192.5
Operating Segments | Global Corporate Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	672.2	592.8	519
General and administrative expenses	[1],[3]	323	300	292.4
Equity in earnings (losses) of equity method investees—net	[1]	22.8	16	13.2
Amortization of goodwill and others	[1]	0.7	0.4	0.4
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	371.3	308.4	239.4
Fixed assets	[1],[5]	173.7	161.8	169.5
Operating Segments | Global Markets Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	321.2	388.1	495.9
General and administrative expenses	[1],[3]	258	234.7	224.3
Equity in earnings (losses) of equity method investees—net	[1]	0	0	0
Amortization of goodwill and others	[1]	0.8	0.8	0.8
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	62.4	152.6	270.8
Fixed assets	[1],[5]	87.9	88.5	98.1
Operating Segments | Asset Management Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	55.2	59.5	50.8
General and administrative expenses	[1],[3]	35.2	33.4	33
Equity in earnings (losses) of equity method investees—net	[1]	0.2	1.5	1.2
Amortization of goodwill and others	[1]	6.8	7.2	7.6
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	13.4	20.4	11.4
Fixed assets	[1],[5]	0	0	0
Others
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2],[6]	25.3	4.7	(39.8)
General and administrative expenses	[1],[3],[6]	48.5	21.8	6.7
Equity in earnings (losses) of equity method investees—net	[1],[6]	(0.5)	(1.8)	(3.8)
Amortization of goodwill and others	[1],[6]	0.9	1	1
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4],[6]	(24.6)	(19.9)	(51.3)
Fixed assets	[1],[5],[6]	¥ 777.6	¥ 794.9	¥ 762.8
[1]Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.[2]“Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated basis and net gains (losses) on operating investment securities of MHSC on its consolidated basis. For the fiscal years ended March 31, 2021, 2022 and 2023, net gains (losses) related to ETFs and others amounted to ¥2.0 billion, ¥1.9 billion and ¥1.8 billion, respectively, of which ¥(1.3) billion, ¥2.3 billion and ¥(0.3) billion are included in “Global Markets Company,” respectively.[3]“General and administrative expenses” excludes non-allocated gains (losses), net.[4]Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses (excluding non-allocated gains (losses), net) plus equity in earnings (losses) of equity method investees—net less amortization of goodwill and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan.[5]“Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net; Goodwill; Intangible assets; and right-of-use assets related to operating leases included in Other assets. The above table does not include other asset amounts because “Fixed assets” is the only balance sheet metric that management uses when evaluating and making decisions pertaining to the operating segments. “Others” in “Fixed assets” includes assets of headquarters that have not been allocated to each segment, “Fixed assets” pertaining to consolidated subsidiaries that are not subject to allocation, consolidating adjustments, and others. Certain “Fixed assets” expenses have been allocated to each segment using reasonable allocation criteria.[6]“Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including elimination of internal transaction between each segment; • equity in earnings (losses) of equity method investees—net that are not subject to allocation; and • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value.

Business Segment Information _2

Business Segment Information (Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others	[1],[2]	¥ 2,280.2	¥ 2,254.5	¥ 2,200.8
Exchange Traded Funds
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others		1.8	1.9	2
Global Markets Company | Exchange Traded Funds
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others		¥ (0.3)	¥ 2.3	¥ (1.3)
[1]Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.[2]“Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated basis and net gains (losses) on operating investment securities of MHSC on its consolidated basis. For the fiscal years ended March 31, 2021, 2022 and 2023, net gains (losses) related to ETFs and others amounted to ¥2.0 billion, ¥1.9 billion and ¥1.8 billion, respectively, of which ¥(1.3) billion, ¥2.3 billion and ¥(0.3) billion are included in “Global Markets Company,” respectively.

Business Segment Information _3

Business Segment Information (Reconciliation of Total Net Business Profits under Internal Management Reporting Systems to Income Before Income Tax Expense on Consolidated Statements of Income) (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net business profits (losses) + Net gains (losses) related to ETFs and others	¥ 807.1	¥ 853.2	¥ 799.8
Adjustment to reconcile management reporting to Japanese GAAP:
General and administrative expenses: non-allocated gains (losses), net	39.7	33.7	6.3
Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans)	(96.7)	(255.9)	(209.9)
Gains on reversal of reserves for possible losses on loans, and others	7.4	20.8	4.9
Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others	84.6	(45.8)	10.1
Net extraordinary gains (losses)	(10.6)	44	115.9
Others	(52.5)	(46.1)	(74.9)
Income before income tax expense under Japanese GAAP	779	603.9	652.2
Adjustment to reconcile Japanese GAAP to U.S. GAAP:
Derivative financial instruments and hedging activities	(373.2)	(124)	(86.4)
Investments	(210.5)	(600.1)	523.5
Loans	(30.3)	(18.3)	(16.9)
Allowances for credit losses	(9.8)	51.5	83.3
Premises and equipment	(29.3)	(68.5)	(56.5)
Land revaluation	5.6	6.4	6.4
Business combinations	8.9	6.9	(1)
Pension liabilities	(71.6)	(94.4)	(153.2)
Consolidation of variable interest entities	0.8	42.3	104.6
Foreign currency translation	(5.2)	(51)	(31.5)
Others	4.8	2.8	4.3
Income (loss) before income tax expense (benefit) under U.S. GAAP	¥ 69.2	¥ (242.5)	¥ 1,028.8

Business Segment Information _4

Business Segment Information (Reconciliation of Assets from Segment to Consolidated) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Schedule Of Assets By Segment [Line Items]
Fixed assets	[1],[2]	¥ 1,678.6	¥ 1,697.3	¥ 1,755.7
U.S. GAAP adjustments	[3]	662.6	717.6	816.1
Premises and equipment-net, Goodwill, Intangible assets, and right-of-use assets related to operating leases included in Other assets		¥ 2,341.2	¥ 2,414.9	¥ 2,571.8
[1]Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.[2]“Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net; Goodwill; Intangible assets; and right-of-use assets related to operating leases included in Other assets. The above table does not include other asset amounts because “Fixed assets” is the only balance sheet metric that management uses when evaluating and making decisions pertaining to the operating segments. “Others” in “Fixed assets” includes assets of headquarters that have not been allocated to each segment, “Fixed assets” pertaining to consolidated subsidiaries that are not subject to allocation, consolidating adjustments, and others. Certain “Fixed assets” expenses have been allocated to each segment using reasonable allocation criteria.[3]The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from right-of-use assets related to operating leases not recognized under Japanese GAAP; internally developed software, which was impaired under Japanese GAAP; land, which was revalued under Japanese GAAP; and the consolidation of certain variable interest entities, which are not consolidated under Japanese GAAP.

Foreign Activities (Consolidate

Foreign Activities (Consolidated Income Statement and Total Assets Information by Major Geographic Area) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	[1]	¥ 4,276,900	¥ 2,113,700	¥ 3,497,900
Total expenses	[2]	4,207,700	2,356,200	2,469,100
Income (loss) before income tax expense (benefit)		69,200	(242,500)	1,028,800
Net income (loss)		34,028	(101,471)	818,048
Total assets		248,780,722	231,550,704	221,651,500
Japan
Segment Reporting Information [Line Items]
Total revenue	[1]	1,104,700	991,100	2,290,800
Total expenses	[2]	1,784,100	1,713,800	1,918,200
Income (loss) before income tax expense (benefit)		(679,400)	(722,700)	372,600
Net income (loss)		(554,700)	(509,000)	235,600
Total assets		161,348,700	155,111,200	152,613,700
United States of America
Segment Reporting Information [Line Items]
Total revenue	[1]	1,841,500	562,900	503,800
Total expenses	[2]	1,455,400	265,000	243,500
Income (loss) before income tax expense (benefit)		386,100	297,900	260,300
Net income (loss)		297,200	275,200	227,400
Total assets		45,516,400	36,765,700	31,939,900
Others
Segment Reporting Information [Line Items]
Total revenue	[1]	93,100	41,700	154,500
Total expenses	[2]	84,700	19,000	14,400
Income (loss) before income tax expense (benefit)		8,400	22,700	140,100
Net income (loss)		1,800	18,300	137,200
Total assets		3,579,600	3,667,900	4,405,300
Europe
Segment Reporting Information [Line Items]
Total revenue	[1]	445,900	184,800	188,700
Total expenses	[2]	413,000	189,200	115,800
Income (loss) before income tax expense (benefit)		32,900	(4,400)	72,900
Net income (loss)		19,900	(16,300)	60,900
Total assets		16,634,700	15,795,900	14,150,600
Asia/Oceania excluding Japan, and others
Segment Reporting Information [Line Items]
Total revenue	[1]	791,700	333,200	360,100
Total expenses	[2]	470,500	169,200	177,200
Income (loss) before income tax expense (benefit)		321,200	164,000	182,900
Net income (loss)		269,800	130,300	156,900
Total assets		¥ 21,701,300	¥ 20,210,000	¥ 18,542,000
[1]Total revenue is comprised of Interest and dividend income and Noninterest income.[2]Total expenses are comprised of Interest expense, Provision (credit) for credit losses and Noninterest expenses.

Mizuho Financial Group, Inc.,_3

Mizuho Financial Group, Inc., Parent Company (Condensed Balance Sheets) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Assets:
Cash and due from banking subsidiaries	¥ 2,241,929	¥ 2,290,377
Interest-bearing deposits in banking subsidiaries	65,750,366	49,883,912
Other assets	9,700,960	8,987,242
Total assets	248,780,722	231,550,704	¥ 221,651,500
Liabilities and shareholders' equity:
Long-term debt	14,893,023	12,578,216
Other liabilities	6,316,695	6,260,222
Shareholders' equity	8,915,491	8,914,212
Total liabilities and equity	248,780,722	231,550,704
Parent Company
Assets:
Cash and due from banking subsidiaries	47,425	51,356
Interest-bearing deposits in banking subsidiaries	450	414
Other assets	545,744	648,946
Total assets	18,878,433	18,023,008
Liabilities and shareholders' equity:
Short-term borrowings from a banking subsidiary	810,000	755,000
Long-term debt	8,741,729	7,957,710
Other liabilities	411,213	396,086
Shareholders' equity	8,915,491	8,914,212
Total liabilities and equity	18,878,433	18,023,008
Parent Company | Banking Subsidiaries
Assets:
Investments in subsidiaries and affiliated companies	7,996,767	8,102,149
Long-term loans receivable from subsidiaries	8,768,725	7,942,367
Parent Company | Non Banking Subsidiaries And Affiliated Companies
Assets:
Investments in subsidiaries and affiliated companies	1,075,322	878,776
Long-term loans receivable from subsidiaries	¥ 444,000	¥ 399,000

Mizuho Financial Group, Inc.,_4

Mizuho Financial Group, Inc., Parent Company (Condensed Statements of Income) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Income:
Total	[1]	¥ 4,276,900	¥ 2,113,700	¥ 3,497,900
Expenses:
Interest expense		2,180,064	374,132	467,939
Equity in undistributed net income (loss) of subsidiaries and affiliated companies—net	[2]	(26,999)	34,587	31,027
Income tax expense (benefit)		35,142	(141,017)	210,716
Net income (loss) attributable to MHFG shareholders		(14,009)	(104,722)	581,765
Parent Company
Income:
Management fees from subsidiaries		43,900	40,462	36,334
Interest income on loans and discounts		177,137	133,215	128,697
Gains on sales of investments in subsidiaries		0	53,005	40
Other income		37,319	11,319	11,970
Total		530,311	517,823	409,013
Expenses:
Operating expenses		52,887	43,192	37,979
Interest expense		175,723	130,453	130,812
Losses on sales of investments in a subsidiary		0	26,606	0
Other expense		2,768	5,946	8,842
Total		231,378	206,197	177,633
Equity in undistributed net income (loss) of subsidiaries and affiliated companies—net		(307,879)	(505,891)	341,369
Income (loss) before income tax expense (benefit)		(8,946)	(194,265)	572,749
Income tax expense (benefit)		5,063	(89,543)	(9,016)
Net income (loss) attributable to MHFG shareholders		(14,009)	(104,722)	581,765
Parent Company | Banking Subsidiary
Income:
Banking subsidiaries		209,257	197,717	214,473
Parent Company | Non Banking Subsidiaries And Affiliated Companies
Income:
Banking subsidiaries		¥ 62,698	¥ 82,105	¥ 17,499
[1]Total revenue is comprised of Interest and dividend income and Noninterest income.[2]These amounts are revenues from contracts that do not meet the scope of ASC 606.

Mizuho Financial Group, Inc.,_5

Mizuho Financial Group, Inc., parent company (Condensed statements of cash flows) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net income (loss)	¥ (14,009)	¥ (104,722)	¥ 581,765
Net cash provided by operating activities	1,006,913	5,498,087	468,756
Cash flows from investing activities:
Purchases of premises and equipment	(185,583)	(136,238)	(211,495)
Purchases of investments in a subsidiary	(48,887)	(93,005)	(47,515)
Net cash provided by (used in) investing activities	6,190,488	(5,016,128)	(2,613,292)
Cash flows from financing activities:
Net change in short-term borrowings	(4,338,379)	(1,711,421)	4,085,165
Proceeds from issuance of long-term debt	4,701,954	3,004,293	2,568,730
Repayment of long-term debt	(2,985,756)	(2,715,054)	(1,511,050)
Purchases of treasury stock	(2,314)	(1,927)	(1,849)
Net cash provided by financing activities	7,762,851	1,991,438	8,691,908
Net increase in cash and cash equivalents	15,818,006	3,440,193	6,782,982
Cash and cash equivalents at beginning of fiscal year	52,174,289	48,734,096	41,951,114
Cash and cash equivalents at end of fiscal year	67,992,295	52,174,289	48,734,096
Parent Company
Cash flows from operating activities:
Net income (loss)	(14,009)	(104,722)	581,765
Adjustments and other	394,191	351,484	(390,748)
Net cash provided by operating activities	380,182	246,762	191,017
Cash flows from investing activities:
Net change in loans	(511,934)	(72,313)	(1,167,385)
Purchases of premises and equipment	(81)	(26)	(41,382)
Proceeds from sales of premises and equipment	0	11	55,624
Purchases of investments in a subsidiary	(179,210)	0	0
Proceeds from sales of investments in subsidiaries	721	452,500	125
Net change in other investing activities	(5,591)	223	(1,370)
Net cash provided by (used in) investing activities	(696,095)	380,395	(1,154,388)
Cash flows from financing activities:
Net change in short-term borrowings	55,000	(95,000)	(10,000)
Proceeds from issuance of long-term debt	1,497,032	930,033	1,477,385
Repayment of long-term debt	(1,030,099)	(1,256,720)	(310,000)
Purchases of treasury stock	(1,575)	(1,927)	(1,849)
Dividends paid	(209,457)	(196,783)	(190,498)
Net change in other financing activities	1,117	44	65
Net cash provided by financing activities	312,018	(620,353)	965,103
Net increase in cash and cash equivalents	(3,895)	6,804	1,732
Cash and cash equivalents at beginning of fiscal year	51,770	44,966	43,234
Cash and cash equivalents at end of fiscal year	¥ 47,875	¥ 51,770	¥ 44,966