Mizuho Financial (MFG) 6-K/A 29 Dec 21 2021 Q2 Current report (foreign) (amended) Financial data

Cover Page

Cover Page	6 Months Ended
	Sep. 30, 2021
Document Information [Line Items]
Document Type	6-K/A
Amendment Flag	true
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Registrant Name	Mizuho Financial Group, Inc.
Entity Central Index Key	0001335730
Current Fiscal Year End Date	--03-31
Amendment Description	Mizuho Financial Group, Inc. previously furnished Form 6-K to the U.S. Securities and Exchange Commission on December 27, 2021 (the “Form 6-K”) and subsequently found that it had inadvertently failed to include certain disclosure under “Financial Condition” in the Form 6-K. This report on Form 6-K/A amends and restates the Form 6-K in its entirety to include such disclosure. Other than as expressly set forth above, this Form 6-K/A does not, and does not purport to, amend, update or restate the information in the Form 6-K.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Assets:
Cash and due from banks		¥ 1,681,209	¥ 1,600,555
Interest-bearing deposits in other banks		46,145,119	47,133,541
Call loans and funds sold		481,275	858,806
Receivables under resale agreements		16,932,681	11,623,438
Receivables under securities borrowing transactions		2,408,249	2,694,107
Trading account assets		27,317,435	26,753,109
Investments (Note 3):
Available-for-sale securities (including assets pledged that secured parties are permitted to sell or repledge of ¥1,416,772 million at March 31, 2021 and ¥1,181,431 million at September 30, 2021), net of allowance		26,198,712	27,853,035
Held-to-maturity securities (including assets pledged that secured parties are permitted to sell or repledge of ¥97,949 million at March 31, 2021 and ¥638,229 million at September 30, 2021)	[1],[2]	1,395,648	887,149
Equity securities		4,191,638	3,785,916
Other investments		554,301	515,346
Loans (Notes 4 and 5)		87,185,770	88,580,867
Allowance for credit losses on loans		(665,228)	(650,849)
Loans, net of allowance		86,520,542	87,930,018
Premises and equipment—net		1,746,873	1,811,458
Due from customers on acceptances		218,862	237,348
Accrued income		307,345	316,834
Goodwill		92,695	92,695
Intangible assets		51,944	56,121
Deferred tax assets		38,017	44,970
Other assets (Note 6)		6,487,093	7,457,028
Total assets		222,769,638	221,651,474
Liabilities and equity:
Noninterest-bearing deposits		27,384,101	29,818,303
Interest-bearing deposits		93,537,394	92,037,375
Noninterest-bearing deposits		2,268,745	2,332,218
Interest-bearing deposits		25,809,953	26,822,708
Due to trust accounts		408,840	380,793
Call money and funds purchased		1,431,316	1,312,790
Payables under repurchase agreements (Note 19)		22,277,794	18,607,147
Payables under securities lending transactions (Note 19)		1,441,179	1,208,031
Other short-term borrowings		9,039,376	9,085,912
Trading account liabilities		9,134,179	10,877,538
Bank acceptances outstanding		218,862	237,348
Income taxes payable		55,571	56,665
Deferred tax liabilities		33,241	76,957
Accrued expenses		160,666	194,303
Long-term debt		12,021,499	11,706,471
Other liabilities (Note 6)		7,504,781	7,208,758
Total		212,727,497	211,963,317
MHFG shareholders' equity:
Common stock (Note 7)-no par value, authorized 4,800,000,000 shares at March 31, 2021 and September 30, 2021, and issued 2,539,249,894 shares at March 31, 2021 and September 30, 2021		5,816,365	5,826,863
Retained earnings		3,184,789	2,967,385
Accumulated other comprehensive income(loss), net of tax (Note 8)		355,785	318,114
Less: Treasury stock, at cost-Common stock 3,889,782 shares at March 31, 2021, and 4,599,386 shares at September 30, 2021		(8,164)	(7,124)
Total MHFG shareholders' equity		9,348,775	9,105,238
Noncontrolling interests		693,366	582,919
Total equity		10,042,141	9,688,157
Total liabilities and equity		222,769,638	221,651,474
Consolidated VIEs
Assets:
Cash and due from banks		1,153	315
Interest-bearing deposits in other banks		34,392	46,143
Call loans and funds sold		150,820	269,030
Trading account assets		2,594,147	2,539,589
Investments (Note 3):
Investments		129,096	100,928
Loans, net of allowance		8,390,651	8,277,276
Other assets (Note 6)		499,485	540,124
Total assets		11,799,744	11,773,405
Liabilities and equity:
Payables under securities lending transactions (Note 19)		59,652	73,630
Other short-term borrowings		56,562	36,546
Trading account liabilities		6,551	58,935
Long-term debt		836,880	593,719
Other liabilities (Note 6)		1,020,897	954,599
Total		¥ 1,980,542	¥ 1,717,429
[1]	Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 and included in Accrued income.
[2]	Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale securities were ¥13,617 million at March 31, 2021, and ¥11,466 million at September 30, 2021.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - JPY (¥) ¥ in Millions	Sep. 30, 2021	Mar. 31, 2021
Trading account assets, assets pledged that secured parties are permitted to sell or repledge	¥ 9,959,042	¥ 6,249,224
Available-for-sale securities, assets pledged that secured parties are permitted to sell or repledge	1,181,431	1,416,772
Held-to-maturity securities, assets pledged that secured parties are permitted to sell or repledge	638,229	97,949
Long-term debt, liabilities accounted for at fair value	¥ 2,863,348	¥ 2,703,021
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	4,599,386	3,889,782

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Interest and dividend income:
Loans, including fees		¥ 470,961	¥ 541,675
Investments:
Interest		26,458	31,236
Dividends		37,724	24,875
Trading account assets		109,477	127,785
Call loans and funds sold		779	1,270
Receivables under resale agreements and securities borrowing transactions		12,861	22,894
Deposits in other banks		25,841	22,111
Total interest and dividend income		684,101	771,846
Interest expense:
Deposits		34,732	110,839
Trading account liabilities		28,488	28,208
Call money and funds purchased		492	1,282
Payables under repurchase agreements and securities lending transactions		13,678	33,267
Other short-term borrowings		1,497	11,988
Long-term debt		81,114	85,593
Total interest expense		160,001	271,177
Net interest income		524,100	500,669
Provision (credit) for credit losses (Notes 3 and 5)		46,053	60,633
Net interest income after provision (credit) for credit losses		478,047	440,036
Noninterest income (Note 16):
Fee and commission income		474,916	428,317
Foreign exchange gains (losses)—net	[1]	21,708	22,785
Trading account gains (losses)—net		83,255	257,591
Investment gains (losses)—net:
Debt securities	[1]	(317)	46
Equity securities	[1]	135,070	266,119
Equity in earnings (losses) of equity method investees—net	[1]	16,541	5,788
Gains on disposal of premises and equipment	[1]	1,988	6,849
Other noninterest income	[2],[3]	29,234	23,715
Total noninterest income		762,395	1,011,210
Noninterest expenses:
Salaries and employee benefits		327,085	346,150
General and administrative expenses		294,259	299,350
Occupancy expenses		90,509	93,314
Fee and commission expenses		107,658	93,016
Provision (credit) for credit losses on off-balance-sheet instruments		(4,821)	(7,391)
Other noninterest expenses		42,552	78,966
Total noninterest expenses		857,242	903,405
Income before income tax expense		383,200	547,841
Income tax expense (Note 11)		39,622	137,761
Net income	[4]	343,578	410,080
Less: Net income attributable to noncontrolling interests		30,921	94,194
Net income attributable to MHFG shareholders		¥ 312,657	¥ 315,886
Earnings per common share (Note 10):
Basic net income per common share		¥ 123.24	¥ 124.50
Diluted net income per common share	[5]	123.24	124.49
Dividends per common share		¥ 40	¥ 37.50
[1]	These amounts are revenues from contracts that do not meet the scope of 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 include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 17 “Fair value” for further details.
[4]	The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 8 “Accumulated other comprehensive income (loss), net of tax.”
[5]	For the six months ended September 30, 2020, 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.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Net income	[1]	¥ 343,578	¥ 410,080
Other comprehensive income (loss), net of tax		38,196	142,550
Total comprehensive income		381,774	552,630
Less: Total comprehensive income attributable to noncontrolling interests		31,446	93,413
Total comprehensive income attributable to MHFG shareholders		¥ 350,328	¥ 459,217
[1]	The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 8 “Accumulated other comprehensive income (loss), net of tax.”

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - JPY (¥) ¥ in Millions	Total	Common Stock	Retained Earnings	Retained EarningsCumulative effect of change in accounting principles		Retained EarningsCumulative effect, period of adoption, adjusted balance	Accumulated other comprehensive income (loss)	[2]	Treasury Stock	Parent	Noncontrolling Interest
Balance at beginning of period at Mar. 31, 2020		¥ 5,827,500	¥ 2,700,774	¥ (124,636)	[1]	¥ 2,576,138	¥ (9,494)		¥ (6,415)		¥ 663,259
Purchases of treasury stock									(1,995)
Performance-based stock compensation program		(553)
Change in ownership interests in consolidated subsidiaries		(520)
Disposal of treasury stock									1,386
Net income attributable to MHFG shareholders	¥ 315,886		315,886
Change during period	142,550						143,331
Other			(80)
Transactions between the MHFG Group and the noncontrolling interest shareholders											(356,311)
Dividends paid to noncontrolling interests											(10,284)
Dividends declared			(95,208)
Net income attributable to noncontrolling interests	(94,194)										94,194
Other											(781)
Balance at end of fiscal year at Sep. 30, 2020	9,140,053	5,826,427	2,796,736				133,837		(7,024)	¥ 8,749,976	390,077
Balance at beginning of period at Mar. 31, 2021	9,688,157	5,826,863	2,967,385	¥ 0		¥ 2,967,385	318,114		(7,124)		582,919
Purchases of treasury stock									(2,647)
Performance-based stock compensation program		(538)
Change in ownership interests in consolidated subsidiaries		(9,960)
Disposal of treasury stock									1,607
Net income attributable to MHFG shareholders	312,657		312,657
Change during period	38,196						37,671
Other			(52)
Transactions between the MHFG Group and the noncontrolling interest shareholders											89,808
Dividends paid to noncontrolling interests											(10,807)
Dividends declared			(95,201)
Net income attributable to noncontrolling interests	(30,921)										30,921
Other											525
Balance at end of fiscal year at Sep. 30, 2021	¥ 10,042,141	¥ 5,816,365	¥ 3,184,789				¥ 355,785		¥ (8,164)	¥ 9,348,775	¥ 693,366
[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” 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 8 “Accumulated other comprehensive income (loss), net of tax.”

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	[1]	¥ 343,578	¥ 410,080
Less: Net income attributable to noncontrolling interests		30,921	94,194
Net income attributable to MHFG shareholders		312,657	315,886
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization		115,756	115,614
Provision (credit) for credit losses		46,053	60,633
Investment losses (gains)—net		(134,753)	(266,165)
Equity in losses (earnings) of equity method investees—net	[2]	(16,541)	(5,788)
Foreign exchange losses (gains)—net		35,446	(92,865)
Deferred income tax expense (benefit)		(28,200)	57,807
Net change in trading account assets		(271,232)	(1,784,129)
Net change in trading account liabilities		(1,734,070)	(1,874,766)
Net change in loans held for sale		(16,915)	18,781
Net change in accrued income		13,325	34,404
Net change in accrued expenses		(32,858)	(80,875)
Other—net		480,671	(159,507)
Net cash used in operating activities		(1,230,661)	(3,660,970)
Cash flows from investing activities:
Proceeds from sales of Available-for-sale securities		20,872,060	13,363,620
Proceeds from sales of Equity securities	[3]	992,927	1,413,300
Proceeds from maturities of Available-for-sale securities		26,506,201	12,719,308
Proceeds from maturities of Held-to-maturity securities		79,767	60,947
Purchases of Available-for-sale securities		(45,046,101)	(33,753,387)
Purchases of Held-to-maturity securities		(542,026)	0
Purchases of Equity securities	[3]	(1,311,347)	(1,383,195)
Proceeds from sales of loans		1,038,124	832,515
Net change in loans		496,474	(3,944,882)
Net change in call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		(4,518,794)	6,141,641
Proceeds from sales of premises and equipment		2,806	12,856
Purchases of premises and equipment		(52,234)	(73,768)
Proceeds from sales of investments in subsidiaries (affecting the scope of consolidation)		5,391	25,190
Purchases of investments in subsidiaries (affecting the scope of consolidation)		(50,723)	0
Net cash used in investing activities		(1,527,475)	(4,585,855)
Cash flows from financing activities:
Net change in deposits		(2,187,631)	4,513,597
Net change in call money and funds purchased, and payables under repurchase agreements and securities lending transactions		3,776,203	1,490,083
Net change in due to trust accounts		28,047	313,806
Net change in other short-term borrowings		(71,262)	2,628,438
Proceeds from issuance of long-term debt		1,442,089	1,270,809
Repayment of long-term debt		(1,179,807)	(515,802)
Proceeds from noncontrolling interests		67,785	73,688
Payments to noncontrolling interests		(1,845)	(3,859)
Proceeds from sales of treasury stock		869	839
Purchases of treasury stock		(1,825)	(1,503)
Purchases of treasury stock of subsidiaries		0	(5,414)
Dividends paid		(95,198)	(95,242)
Dividends paid to noncontrolling interests		(10,807)	(10,284)
Net cash provided by financing activities		1,766,618	9,659,156
Effect of exchange rate changes on cash and cash equivalents		83,750	(126,397)
Net increase (decrease) in cash and cash equivalents	[4]	(907,768)	1,285,934
Cash and cash equivalents at beginning of period	[4]	48,734,096	41,951,114
Cash and cash equivalents at end of period	[4]	47,826,328	43,237,048
Noncash investing activities:
Transfer of loans into loans held-for-sale		¥ 15,357	¥ 11,399
[1]	The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 8 “Accumulated other comprehensive income (loss), net of tax.”
[2]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[3]	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.
[4]	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.

Basis of presentation

Basis of presentation	6 Months Ended
	Sep. 30, 2021
Basis of presentation	1. 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 20 “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 interim financial reporting period ends on September 30. Certain of MHFG’s subsidiaries have different interim financial reporting periods than September 30. For those subsidiaries with interim financial reporting periods within three months of MHFG’s interim financial reporting period, the effect of intervening events that materially affect the financial position or results of operations through the date of each of the periods presented in the MHFG’s consolidated financial statements have 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. On October 1, 2020, a 1-for-10 The unaudited interim consolidated financial statements should be read in conjunction with the audited financial statements and related notes included in the MHFG Group’s most recent annual report on Form 20-F for the fiscal year ended March 31, 2021. Certain financial information that is normally included in annual financial statements prepared in accordance with U.S. GAAP, but is not required for interim reporting purposes, has been condensed or omitted. The financial statements reflect all normal and recurring adjustments that are, in the opinion of management, necessary for a fair presentation of the results for the interim periods. 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 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 pandemics, such as COVID-19, Financial instruments—current expected credit losses (“CECL”) The adoption of this guidance established a single allowance framework for all financial assets measured at amortized cost and certain off-balance-sheet losses available-for-sale further impact 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 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 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 ratings 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 consistent to what is used in the MHFG Group’s stress testing and 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 includes the allowance for groups of loans which were collectively evaluated for expected credit losses, in addition to 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 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 troubled debt restructuring (“TDR”) loans 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. Considering internal and external factors affecting the credit quality of the portfolio, the Group incorporated the estimated impact of COVID-19 Allowance and provision (credit) for credit losses on off-balance-sheet The MHFG Group maintains an allowance for credit losses on off-balance-sheet assesses the expected loss amounts for commitments to invest in securities and commitments to extend credit, considering the probability of drawdowns. The allowance is recorded in Other liabilities. Net changes in the allowance for credit losses on off-balance-sheet off-balance-sheet Allowance and provision (credit) for credit losses on available-for-sale The MHFG Group performs periodic reviews impaired Available-for-sale available-for-sale available-for-sale available-for-sale available-for-sale .

Issued accounting pronouncement

Issued accounting pronouncements	6 Months Ended
	Sep. 30, 2021
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.2020-04 No.2021-01

Investments

Investments	6 Months Ended
	Sep. 30, 2021
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 cost (4)(5) Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) March 31, 2021 Available-for-sale Debt securities: Japanese government bonds 20,953,200 1,945 34,562 20,920,583 Japanese local government bonds 463,673 544 658 463,559 U.S. Treasury bonds and federal agency securities 906,499 4,440 46 910,893 Other foreign government bonds 1,505,770 1,975 209 1,507,536 Agency mortgage-backed securities (1) 512,720 8,746 687 520,779 Residential mortgage-backed securities 70,111 761 188 70,684 Commercial mortgage-backed securities 709,938 6,196 39 716,095 Japanese corporate bonds and other debt securities 1,897,117 10,537 3,574 1,904,080 Foreign corporate bonds and other debt securities (2) 837,675 2,577 1,426 838,826 Total 27,856,703 37,721 41,389 27,853,035 Held-to-maturity Debt securities: Japanese government bonds 479,959 9,555 — 489,514 Agency mortgage-backed securities (3) 407,190 10,178 3,273 414,095 Total 887,149 19,733 3,273 903,609 September 30, 2021 Available-for-sale Debt securities: Japanese government bonds 19,029,022 498 26,477 19,003,043 Japanese local government bonds 494,716 713 486 494,943 U.S. Treasury bonds and federal agency securities 1,070,555 3,269 69 1,073,755 Other foreign government bonds 1,331,043 783 889 1,330,937 Agency mortgage-backed securities (1) 591,778 8,467 853 599,392 Residential mortgage-backed securities 63,273 706 137 63,842 Commercial mortgage-backed securities 760,959 6,182 224 766,917 Japanese corporate bonds and other debt securities 1,977,235 9,962 2,774 1,984,423 Foreign corporate bonds and other debt securities (2) 880,838 1,601 979 881,460 Total 26,199,419 32,181 32,888 26,198,712 Held-to-maturity Debt securities: Japanese government bonds 479,970 7,437 — 487,407 Agency mortgage-backed securities (3) 915,678 7,203 6,705 916,176 Total 1,395,648 14,640 6,705 1,403,583 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 ¥520,746 million and ¥33 million, respectively, at March 31, 2021, and ¥599,359 million and ¥33 million, respectively, at September 30, 2021. 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 ¥ (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 (5) Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 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 11,112,193 6,466,555 1,182,864 267,410 19,029,022 Japanese local government bonds 41,016 241,693 204,491 7,516 494,716 U.S. Treasury bonds and federal agency securities 422,693 647,862 — — 1,070,555 Other foreign government bonds 917,929 410,999 1,059 1,056 1,331,043 Agency mortgage-backed securities — — — 591,778 591,778 Residential mortgage-backed securities — — — 63,273 63,273 Commercial mortgage-backed securities 34,244 338,785 385,530 2,400 760,959 Japanese corporate bonds and other debt securities 103,494 996,194 333,038 544,509 1,977,235 Foreign corporate bonds and other debt securities 515,116 292,020 68,649 5,053 880,838 Total 13,146,685 9,394,108 2,175,631 1,482,995 26,199,419 Held-to-maturity Debt securities: Japanese government bonds — 479,970 — — 479,970 Agency mortgage-backed securities — — — 915,678 915,678 Total — 479,970 — 915,678 1,395,648 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 11,111,775 6,460,865 1,166,584 263,819 19,003,043 Japanese local government bonds 41,027 241,790 204,570 7,556 494,943 U.S. Treasury bonds and federal agency securities 423,719 650,036 — — 1,073,755 Other foreign government bonds 917,972 410,850 1,059 1,056 1,330,937 Agency mortgage-backed securities — — — 599,392 599,392 Residential mortgage-backed securities — — — 63,842 63,842 Commercial mortgage-backed securities 34,263 340,915 389,302 2,437 766,917 Japanese corporate bonds and other debt securities 103,477 996,501 332,963 551,482 1,984,423 Foreign corporate bonds and other debt securities 515,240 292,089 69,078 5,053 881,460 Total 13,147,473 9,393,046 2,163,556 1,494,637 26,198,712 Held-to-maturity Debt securities: Japanese government bonds — 487,407 — — 487,407 Agency mortgage-backed securities — — — 916,176 916,176 Total — 487,407 — 916,176 1,403,583 Credit losses The MHFG Group recognized no material allowance for credit loss on available-for-sale held-to-maturity mortgage-backed . 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) March 31, 2021 Available-for-sale Debt securities: Japanese government bonds 9,998,772 1,924 4,058,718 32,638 14,057,490 34,562 Japanese local government bonds 125,058 323 130,384 335 255,442 658 U.S. Treasury bonds and federal agency securities 38,625 46 — — 38,625 46 Other foreign government bonds 576,415 209 — — 576,415 209 Agency mortgage-backed securities (Note) 70,088 120 36,989 567 107,077 687 Residential mortgage-backed securities 9,270 52 11,435 136 20,705 188 Commercial mortgage-backed securities 12,530 6 10,351 33 22,881 39 Japanese corporate bonds and other debt securities 278,698 953 843,026 2,621 1,121,724 3,574 Foreign corporate bonds and other debt securities 233,405 1,426 — — 233,405 1,426 Total 11,342,861 5,059 5,090,903 36,330 16,433,764 41,389 September 30, 2021 Available-for-sale Debt securities: Japanese government bonds 13,200,228 4,197 1,977,981 22,280 15,178,209 26,477 Japanese local government bonds 93,142 137 147,795 349 240,937 486 U.S. Treasury bonds and federal agency securities 39,048 69 — — 39,048 69 Other foreign government bonds 622,377 856 66,431 33 688,808 889 Agency mortgage-backed securities (Note) 81,466 253 61,604 600 143,070 853 Residential mortgage-backed securities 6,862 28 12,074 109 18,936 137 Commercial mortgage-backed securities 42,905 184 9,786 40 52,691 224 Japanese corporate bonds and other debt securities 488,973 830 690,315 1,944 1,179,288 2,774 Foreign corporate bonds and other debt securities 266,866 328 60,191 651 327,057 979 Total 14,841,867 6,882 3,026,177 26,006 17,868,044 32,888 Note: Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥107,077 million at March 31, 2021, and ¥143,070 million at September 30, 2021. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. At September 30, 2021, 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 were 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 were 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 Six months ended September 30, 2020 2021 (in millions of yen) Gross realized gains 5,101 4,687 Gross realized losses (3,694 ) (3,925 ) Net realized gains (losses) on sales of available-for-sale 1,407 762 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 six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Net gains (losses) recognized during the period on equity securities 266,119 135,070 Less: Net gains (losses) recognized during the period on equity securities sold during the period 34,985 29,552 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period 231,134 105,518 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 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Carrying amounts at the end of the period 186,146 208,869 Downward adjustments and impairments 5,087 6,580 Upward adjustments 9,216 24,126 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. Six months ended September 30, 2020 2021 (in millions of yen) Downward adjustments and impairments 1,411 1,704 Upward adjustments 34 14,950 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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Equity method investments 460,025 493,573 Investments held by consolidated investment companies and other 55,321 60,728 Total 515,346 554,301 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 ¥229,156 million and ¥247,864 million, at March 31, 2021 and September 30, 2021, respectively. The aggregate market values of these marketable equity securities were ¥424,267 million and ¥449,650 million, respectively. The majority of the aggregate market values of these marketable equity securities include Orient Corporation, the Chiba Kogyo Bank, Ltd., Joint Stock Commercial Bank for Foreign Trade of Vietnam and Mizuho Leasing Company, Limited of which the MHFG Group’s proportionate share of the total outstanding common stock were %, respectively, as of September 30, 2021. In addition, equity method investments include non-marketable equity securities such as Matthews International Capital Management, LLC and Custody Bank of Japan, Ltd. of which the MHFG Group’s proportionate share of the total outstanding common stock were . 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	6 Months Ended
	Sep. 30, 2021
Loans	4. Loans The table below presents loans outstanding by domicile and industry of borrower at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Domestic: Manufacturing 11,010,644 10,569,793 Construction and real estate 10,492,162 10,664,028 Services 6,406,710 6,002,667 Wholesale and retail 5,357,287 5,432,264 Transportation and communications 3,885,807 3,912,609 Banks and other financial institutions (1) 4,695,677 4,231,331 Government and public institutions 1,898,137 1,596,867 Other industries (2) 5,918,260 5,997,987 Individuals: Mortgage loans 8,193,398 8,039,138 Other 790,184 758,680 Total domestic 58,648,266 57,205,364 Foreign: Commercial and industrial (3) 19,454,623 19,368,406 Banks and other financial institutions (4) 10,448,778 10,561,219 Government and public institutions 177,385 192,055 Other 18,843 24,362 Total foreign 30,099,629 30,146,042 Total 88,747,895 87,351,406 Less: Unearned income and deferred loan fees-net 167,028 165,636 Total loans before allowance for credit losses on loans 88,580,867 87,185,770 Notes: (1) Banks and other financial institutions of domestic includes mainly banks, securities companies, insurance companies and credit card companies. (2) Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs. (3) Commercial and industrial of foreign includes ¥221,908 million and ¥221,144 million of lease receivables that are receivables arising from direct financing leasing at March 31, 2021 and September 30, 2021, respectively. (4) Banks and other financial institutions of foreign includes mainly banks and financial services companies. 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. Net losses on sales of loans were ¥1,178 million and ¥1,674 million for the six months ended September 30, 2020 and 2021, respectively. These net losses include unrealized gains and losses from making loans classified as held for sale to the lower of cost or fair value at the end of each reporting period. The gains and losses on sales of loans are recorded in Other noninterest income and expenses, respectively. 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 receivables at September 30, 2021 was ¥73,807 million and included in Accrued income. The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2021 and September 30, 2021: 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, 2021 and September 30, 2021: March 31, 2021 Term loans by origination year Revolving Loans Total 2020 2019 2018 2017 2016 Prior to 2016 (in millions of yen) Domestic: Corporate: Large companies: Normal obligors 14,351,596 6,173,182 6,884,219 2,384,565 2,105,541 2,256,613 6,819,851 40,975,567 Watch obligors excluding special attention obligors 151,406 86,390 86,199 61,785 40,907 35,681 128,363 590,731 Nonaccrual loans 219,111 196,945 38,490 129,066 28,650 9,547 194,607 816,416 Small and medium-sized Normal obligors 633,438 463,744 397,656 224,791 205,687 502,707 518,612 2,946,635 Watch obligors excluding special attention obligors 62,300 24,245 30,007 13,547 13,536 24,430 29,041 197,106 Nonaccrual loans 78,238 10,794 7,341 5,168 3,154 8,852 28,853 142,400 Retail: Housing Loan: Normal obligors 785,194 588,599 588,535 600,179 741,969 4,599,546 — 7,904,022 Watch obligors excluding special attention obligors 2,041 1,075 1,566 1,343 2,127 39,046 — 47,198 Nonaccrual loans 20,706 2,268 1,399 1,421 1,640 35,135 — 62,569 Others: Normal obligors 431,277 154,675 127,379 88,649 85,042 317,237 526,703 1,730,962 Watch obligors excluding special attention obligors 50,212 14,288 10,450 5,888 3,713 5,796 10,545 100,892 Nonaccrual loans 32,594 2,086 1,145 901 837 8,780 12,557 58,900 Sovereign: Normal obligors 1,466,468 80,260 128,702 71,943 75,389 389,777 12,615 2,225,154 Watch obligors excluding special attention obligors 4,312 3,594 2,164 635 31 — — 10,736 Nonaccrual loans — — — — — — — — Banks and other financial institutions (4): Normal obligors 51,874 135,135 241,418 24,097 84,244 60,281 162,622 759,671 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 18,340,767 7,937,280 8,546,670 3,613,978 3,392,467 8,293,428 8,444,369 58,568,959 Foreign: Corporate: Normal obligors 12,813,813 4,614,310 2,558,432 922,526 655,823 1,143,658 4,501,155 27,209,717 Watch obligors excluding special attention obligors 196,054 36,915 72,529 54,514 894 25,009 127,553 513,468 Nonaccrual loans 61,657 29,657 12,547 3,034 4,417 17,394 14,580 143,286 Retail: Normal obligors 2,100 2,342 1,468 1,034 1,074 1,401 18 9,437 Watch obligors excluding special attention obligors — — — 14 — 13 — 27 Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 96,177 78,727 26,569 157,256 — 4,474 69,320 432,523 Watch obligors excluding special attention obligors — — — — — 20,118 — 20,118 Nonaccrual loans — 710 — — — — — 710 Banks and other financial institutions (5) Normal obligors 1,030,080 317,635 275,695 18,272 1,497 3,105 25,145 1,671,429 Watch obligors excluding special attention obligors 6,341 — 78 — 4,774 — — 11,193 Nonaccrual loans — — — — — — — — Total foreign 14,206,222 5,080,296 2,947,318 1,156,650 668,479 1,215,172 4,737,771 30,011,908 Total 32,546,989 13,017,576 11,493,988 4,770,628 4,060,946 9,508,600 13,182,140 88,580,867 September 30, 2021 Term loans by origination year Revolving Total 2021 2020 2019 2018 2017 Prior to 2017 (in millions of yen) Domestic: Corporate: Large companies: Normal obligors 8,189,714 8,020,885 5,614,210 6,241,858 2,078,317 3,590,252 6,537,575 40,272,811 Watch obligors excluding special attention obligors 81,285 96,286 84,448 81,316 47,014 64,902 140,816 596,067 Nonaccrual loans 84,652 121,840 198,406 38,431 136,798 54,315 199,683 834,125 Small and medium-sized Normal obligors 308,157 496,873 431,411 339,670 203,267 563,176 521,714 2,864,268 Watch obligors excluding special attention obligors 33,846 36,441 31,820 27,171 13,205 34,406 30,506 207,395 Nonaccrual loans 62,960 22,583 8,509 3,328 2,391 9,516 31,481 140,768 Retail: Housing Loan: Normal obligors 447,717 614,629 550,698 556,355 571,772 5,039,717 — 7,780,888 Watch obligors excluding special attention obligors 481 1,894 845 1,783 1,142 40,431 — 46,576 Nonaccrual loans 10,775 7,452 1,175 1,349 1,100 33,144 — 54,995 Others: Normal obligors 130,034 319,234 131,507 107,610 73,837 353,742 507,467 1,623,431 Watch obligors excluding special attention obligors 18,393 41,274 13,092 9,820 5,015 8,469 9,915 105,978 Nonaccrual loans 28,342 9,376 1,800 1,062 899 8,949 12,973 63,401 Sovereign: Normal obligors 844,284 266,527 85,704 125,215 72,379 425,654 1,100 1,820,863 Watch obligors excluding special attention obligors 951 5,118 1,145 576 161 — — 7,951 Nonaccrual loans — — — — — — — — Banks and other financial institutions (4) Normal obligors 48,602 24,845 132,967 221,456 — 144,044 139,047 710,961 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 10,290,193 10,085,257 7,287,737 7,757,000 3,207,297 10,370,717 8,132,277 57,130,478 Foreign: Corporate: Normal obligors 9,887,658 4,993,722 4,023,459 1,961,077 730,828 1,347,278 4,614,140 27,558,162 Watch obligors excluding special attention obligors 149,058 106,849 40,203 44,477 19,720 16,717 110,385 487,409 Nonaccrual loans 15,194 17,043 36,032 7,935 765 20,188 8,714 105,871 Retail: Normal obligors 1,130 1,569 1,978 1,199 522 3,510 17 9,925 Watch obligors excluding special attention obligors — — 40 — — 14 — 54 Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 65,240 44,751 53,723 24,142 158,689 3,532 61,176 411,253 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — 653 — — — — 653 Banks and other financial institutions (5) Normal obligors 636,823 345,528 197,395 249,809 16,127 1,506 28,627 1,475,815 Watch obligors excluding special attention obligors — 5,390 152 608 — — — 6,150 Nonaccrual loans — — — — — — — — Total foreign 10,755,103 5,514,852 4,353,635 2,289,247 926,651 1,392,745 4,823,059 30,055,292 Total 21,045,296 15,600,109 11,641,372 10,046,247 4,133,948 11,763,462 12,955,336 87,185,770 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 six months ended September 30, 2021. (4) Banks and other financial institutions of domestic includes mainly banks and securities companies (5) Banks and other financial institutions of foreign includes mainly banks. Nonaccrual loans 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 payment of the principal and interest when due. The Group classifies loans to special attention, intensive control, substantially bankrupt and bankrupt obligors as nonaccrual loans. Nonaccrual loans include loans past due for 90 days or more and restructured loans that meet the definition of a TDR in accordance with ASC 310. 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 In March 2020, the Coronavirus, Aid, Relief, and Economic Security Act (“the CARES Act”) was approved. The CARES Act and U.S. banking agencies have among other items, provided optional, temporary relief related to accounting for certain TDRs. The temporary TDR relief is available to banks for loan modifications related to obligors who were adversely impacted by COVID-19. With regard to 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 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 status, when the borrower qualifies for an obligor rating of D or above. The table below presents nonaccrual loans information at March 31, 2021 and September 30, 2021: Amortized cost Nonaccrual loans with an allowance Nonaccrual loans without an allowance Total nonaccrual loans Interest income recognized (in millions of yen) March 31, 2021 Domestic: Corporate: Large companies 800,329 16,087 816,416 13,050 Small and medium-sized 121,031 21,369 142,400 1,759 Retail: Housing Loan 37,006 25,563 62,569 1,073 Others 37,884 21,016 58,900 806 Total domestic 996,250 84,035 1,080,285 16,688 Foreign: Total foreign 117,300 26,696 143,996 2,422 Total 1,113,550 110,731 1,224,281 19,110 September 30, 2021 Domestic: Corporate: Large companies 815,107 19,018 834,125 6,787 Small and medium-sized 123,862 16,906 140,768 867 Retail: Housing Loan 31,588 23,407 54,995 477 Others 40,762 22,639 63,401 406 Total domestic 1,011,319 81,970 1,093,289 8,537 Foreign: Total foreign 98,892 7,632 106,524 843 Total 1,110,211 89,602 1,199,813 9,380 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 ¥20,197 million and ¥14,887 million as of March 31, 2021 and September 30, 2021 respectively. 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 six months ended September 30, 2020 and 2021: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in millions of yen) September 30, 2020 Domestic: Corporate: Large companies — — 264,952 Small and medium-sized — — 54,760 Retail: Housing Loan — — 14,690 Others — — 9,130 Banks and other financial institutions — — 1,600 Total domestic — — 345,132 Foreign: Total foreign — — 80,889 Total — — 426,021 September 30, 2021 Domestic: Corporate: Large companies 5,849 22,757 375,248 Small and medium-sized — — 60,856 Retail: Housing Loan — — 4,996 Others — — 10,288 Total domestic 5,849 22,757 451,388 Foreign: Total foreign — — 21,206 Total 5,849 22,757 472,594 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 six months ended September 30, 2020 and 2021 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment September 30, 2020 September 30, 2021 (in millions of yen) Domestic: Corporate: Large companies 2,084 1,148 Small and medium-sized 3,861 2,157 Retail: Housing Loan 505 579 Others 1,104 515 Total domestic 7,554 4,399 Foreign: Total foreign 43,786 14,125 Total 51,340 18,524 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, 2021 and September 30, 2021: 30-59 days past due 60-89 days past due 90 days or more past Total past due Current Total (in millions of yen) March 31, 2021 Domestic: Corporate: Large companies 1,275 4,607 27,387 33,269 42,349,445 42,382,714 Small and medium-sized 1,386 — 9,185 10,571 3,275,570 3,286,141 Retail: Housing Loan 9,776 7,102 21,257 38,135 7,975,654 8,013,789 Others 5,165 1,123 12,012 18,300 1,872,454 1,890,754 Sovereign — — — — 2,235,890 2,235,890 Banks and other financial institutions — — — — 759,671 759,671 Total domestic 17,602 12,832 69,841 100,275 58,468,684 58,568,959 Foreign: Total foreign — 7,477 30,795 38,272 29,973,636 30,011,908 Total 17,602 20,309 100,636 138,547 88,442,320 88,580,867 30-59 days past due 60-89 days past due 90 days or more past Total past due Current Total (in millions of yen) September 30, 2021 Domestic: Corporate: Large companies — 3,149 22,168 25,317 41,677,686 41,703,003 Small and medium-sized 1,794 336 9,490 11,620 3,200,811 3,212,431 Retail: Housing Loan 14,521 7,250 19,092 40,863 7,841,596 7,882,459 Others 5,034 1,056 12,272 18,362 1,774,448 1,792,810 Sovereign — — — — 1,828,814 1,828,814 Banks and other financial institutions — — — — 710,961 710,961 Total domestic 21,349 11,791 63,022 96,162 57,034,316 57,130,478 Foreign: Total foreign — — 23,004 23,004 30,032,288 30,055,292 Total 21,349 11,791 86,026 119,166 87,066,604 87,185,770 Note: The majority of total foreign consist of corporate. Loans held for sale Loans that have been identified for sale are classified as loans held for sale within O Collateral Dependent Loans The MHFG 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 September 30, 2021, collateral relating to these loans comprised of real estate, exchange traded equity securities and deposits, etc., and primarily collateral type was real estate. There were no significant changes in the extent to which collateral secures these loans during this fiscal year and no significant concentration of collateral against any portfolio segment.

Allowance for credit losses on

Allowance for credit losses on loans	6 Months Ended
	Sep. 30, 2021
Allowance for credit losses on loans	5. Allowance for credit losses on loans 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. When management estimates current expected credit losses to determine the allowance for credit losses, small balance, homogeneous loans are classified in the retail portfolio segment, and loans other than these are classified in the corporate portfolio segment. 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 also includes loans of subsidiaries other than MHBK and MHTB, such as consolidated VIEs and overseas subsidiaries. The corporate portfolio segment is divided into two classes based on their risk characteristics: large companies, and small and medium-sized Changes in Allowance for credit losses on loans by portfolio segment for the six months ended September 30, 2020 and 2021 are shown below: Corporate Retail Total (in millions of yen) Six months ended September 30, 2020 Balance at beginning of period 413,026 27,829 440,855 April 1, 2020 adoption of CECL 77,514 78,241 155,755 Adjusted Balance at beginning of period 490,540 106,070 596,610 Provision (credit) for credit losses on loans 64,133 (11,051 ) 53,082 Charge-offs (28,417 ) (3,446 ) (31,863 ) Recoveries 5,260 479 5,739 Net charge-offs (23,157 ) (2,967 ) (26,124 ) Others (Note) (997 ) (45 ) (1,042 ) Balance at end of period 530,519 92,007 622,526 Six months ended September 30, 2021 Balance at beginning of period 562,470 88,379 650,849 Provision (credit) for credit losses on loans 49,695 (1,490 ) 48,205 Charge-offs (38,473 ) (2,423 ) (40,896 ) Recoveries 5,827 664 6,491 Net charge-offs (32,646 ) (1,759 ) (34,405 ) Others (Note) 579 — 579 Balance at end of period 580,098 85,130 665,228 Note: Others includes primarily foreign exchange translation.

Other assets and liabilities

Other assets and liabilities	6 Months Ended
	Sep. 30, 2021
Other assets and liabilities	6. Other assets and liabilities The following table sets forth the details of other assets and liabilities at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions 2,339,902 1,668,239 Other 393,410 414,363 Collateral pledged: Collateral pledged for derivative transactions 1,088,847 900,101 Margins provided for futures contracts 297,496 338,584 Other 939,557 888,466 Prepaid pension cost 999,962 851,035 Right-of-use 611,533 594,381 Security deposits 104,915 103,728 Loans held for sale 29,834 46,749 Other 651,572 681,447 Total 7,457,028 6,487,093 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions 2,576,887 2,450,159 Other 403,501 425,615 Guaranteed trust principal (Note) 814,509 807,635 Lease 636,541 615,846 Collateral accepted: Collateral accepted for derivative transactions 763,642 721,662 Margins accepted for futures contracts 555,760 913,262 Unearned income 120,521 113,450 Other 1,337,397 1,457,152 Total 7,208,758 7,504,781 Note: 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 15 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred and common stock

Preferred and common stock	6 Months Ended
	Sep. 30, 2021
Preferred and common stock	7. Preferred and common stock Preferred stock The composition of preferred stock at March 31, 2021 and September 30, 2021 is as follows: Class of stock March 31, 2021 September 30, 2021 Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 90,000,000 — 90,000,000 — Class XV preferred stock 90,000,000 — 90,000,000 — Class XVI preferred stock 150,000,000 — 150,000,000 — Common stock The number of issued shares of common stock at March 31, 2021 and September 30, 2021 was 2,539,249,894. There was no increase or decrease during the six months ended September 30, 2021.

Accumulated other comprehensive

Accumulated other comprehensive income (loss), net of tax	6 Months Ended
	Sep. 30, 2021
Accumulated other comprehensive income (loss), net of tax	8. Accumulated other comprehensive income (loss), net of tax Changes in each component of Accumulated other comprehensive income (loss), net of tax (“AOCI”) for the six months ended September 30, 2020 and 2021 are as follows: Six months ended September 30, 2020 2021 (in millions of yen) AOCI, balance at beginning of period (9,494 ) 318,114 Net unrealized gains (losses) on available-for-sale Balance at beginning of period (19,592 ) (8,173 ) Unrealized holding gains (losses) during period 644 6,034 Less: reclassification adjustments for losses (gains) included in net income 754 (525 ) Change during period 1,398 5,509 Balance at end of period (18,194 ) (2,664 ) Foreign currency translation adjustments: Balance at beginning of period (109,872 ) (86,873 ) Foreign currency translation adjustments during period (36,652 ) 52,231 Less: reclassification adjustments for losses (gains) included in net income (409 ) — Change during period (37,061 ) 52,231 Balance at end of period (146,933 ) (34,642 ) Pension liability adjustments: Balance at beginning of period 69,455 397,153 Unrealized gains (losses) during period 190,394 (5,107 ) Less: reclassification adjustments for losses (gains) included in net income 672 (9,187 ) Change during period 191,066 (14,294 ) Balance at end of period 260,521 382,859 Own credit risk adjustments: Balance at beginning of period 50,515 16,007 Unrealized gains (losses) during period (9,340 ) (6,218 ) Less: reclassification adjustments for losses (gains) included in net income (2,732 ) 443 Change during period (12,072 ) (5,775 ) Balance at end of period 38,443 10,232 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 143,331 37,671 AOCI, balance at end of period 133,837 355,785 The following table shows the amounts reclassified out of AOCI into net income during the six months ended Sept e Six months ended September 30, 2021 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 income: Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale 738 (213 ) 525 — 525 Investment gains (losses)-net Pension liability adjustments 13,074 (3,875 ) 9,199 (12 ) 9,187 Salaries and employee Own credit risk adjustments (714 ) 219 (495 ) 52 (443 ) Other noninterest income Total 13,098 (3,869 ) 9,229 40 9,269 Notes: (1) The financial statement line item in which the amou n (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 and Net income, respectively.

Regulatory matters

Regulatory matters	6 Months Ended
	Sep. 30, 2021
Regulatory matters	9. Regulatory matters Regulatory capital requirements MHFG, MHBK, and MHTB are subject to regulatory capital requirements administered 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. Capital adequacy ratios and leverage ratios of MHFG, MHBK, and MHTB as of March 31, 2021 and September 30, 2021 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: March 31, 2021 September 30, 2021 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (1) 5,405 8.01 5,379 8.01 Actual 7,850 11.63 8,244 12.27 Tier 1 capital: Required (1) 6,418 9.51 6,386 9.51 Actual 9,702 14.37 10,098 15.03 Total risk-based capital: Required (1) 7,767 11.51 7,729 11.51 Actual 11,385 16.87 11,927 17.76 Leverage Ratio (2) Required 6,016 3.00 6,108 3.00 Actual 9,702 4.83 10,098 4.96 MHBK: Common Equity Tier 1 capital: Required 2,823 4.50 2,794 4.50 Actual 6,972 11.11 7,340 11.82 Tier 1 capital: Required 3,764 6.00 3,726 6.00 Actual 8,819 14.05 9,187 14.79 Total risk-based capital: Required 5,019 8.00 4,967 8.00 Actual 10,400 16.57 10,924 17.59 Leverage Ratio (2) Required 5,660 3.00 5,700 3.00 Actual 8,819 4.67 9,187 4.83 MHTB: Common Equity Tier 1 capital: Required 82 4.50 81 4.50 Actual 527 28.94 479 26.70 Tier 1 capital: Required 109 6.00 108 6.00 Actual 527 28.94 479 26.70 Total risk-based capital: Required 146 8.00 144 8.00 Actual 527 28.94 479 26.71 Leverage Ratio (2) Required 138 3.00 129 3.00 Actual 527 11.41 479 11.17 March 31, 2021 September 30, 2021 Amount Ratio Amount Ratio (in billions of yen, except percentages) Non-consolidated: MHBK: Common Equity Tier 1 cap i Required 2,648 4.50 2,619 4.50 Actual 6,561 11.14 6,790 11.66 Tier 1 capital: Required 3,531 6.00 3,492 6.00 Actual 8,406 14.28 8,635 14.83 Total risk-based capital: Required 4,708 8.00 4,656 8.00 Actual 9,987 16.96 10,355 17.79 Leverage Ratio (2) Required 5,343 3.00 5,373 3.00 Actual 8,406 4.72 8,635 4.82 MHTB: Common Equity Tier 1 capital: Required 82 4.50 80 4.50 Actual 519 28.63 465 26.03 Tier 1 capital: Required 109 6.00 107 6.00 Actual 519 28.63 465 26.03 Total risk-based capital: Required 145 8.00 143 8.00 Actual 519 28.64 465 26.04 Leverage Ratio (2) Required 135 3.00 125 3.00 Actual 519 11.51 465 11.15 Notes: (1) The required ratios disclosed above, at March 31, 2021 and September 30, 2021, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01%, and the additional loss absorbency requirements for global systemically important banks (“G-SIBs”) (“D-SIBs”) (2) The required and actual amounts disclosed above at March 31, 2021 and September 30, 2021 exclude amounts of deposits to the Bank of Japan. MHFG’s securities subsidiary in Japan is also subject to the capital adequacy requirement under Japan’s Financial Instruments and Exchange Act. Failure to maintain a minimum capital ratio will trigger mandatory regulatory actions. 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 which they were subject. Business improvement orders In September and November 2021, MHFG and MHBK received business improvement orders from the Financial Services Agency of Japan, pursuant to the provisions of Article 52-33, Paragraph 1 and Article 26, Paragraph 1 of the Banking Act of Japan, in regard to the series of IT system failures that have occurred from February to September 2021. MHFG and MHBK has been and will be formulating and implementing the business improvement plans and measures so that further similar incidents will be prevented. See Note 14 “Commitments and contingencies” for further information on the impact that these orders have on the consolidated financial statements.

Earnings per common share

Earnings per common share	6 Months Ended
	Sep. 30, 2021
Earnings per common share	10. Earnings per common share Basic earnings per common share are computed by dividing net income attributable to MHFG common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share reflect all dilutive potential common shares such as stock options and the common shares of MHFG under the stock compensation programs. The following table sets forth the computation of basic and diluted earnings per common share for the six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Net income: Net income attributable to MHFG common shareholders 315,886 312,657 Effect of dilutive securities — — Net income attributable to common shareholders after assumed conversions 315,886 312,657 Six months ended September 30, 2020 2021 (thousands of shares) Shares: Weighted average common shares outstanding 2,537,272 2,536,902 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 93 119 Weighted average common shares after assumed conversions 2,537,365 2,537,021 Six months ended September 30, 2020 2021 (in yen) Earnings per common share: Basic net income per common share 124.50 123.24 Diluted net income per common share (Note) 124.49 123.24 Note: For the six months ended September 30, 2020, 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.

Income taxes

Income taxes	6 Months Ended
	Sep. 30, 2021
Income taxes	11. Income taxes The following table presents the components of Income tax expense for the six months ended September 30, 2020 and 2021: Six months ended 2020 2021 (in millions of yen) Current tax expense 79,954 67,822 Deferred tax expense (benefit) 57,807 (28,200 ) Total income tax expense 137,761 39,622 The preceding table does not reflect the tax effects of items recorded directly in Equity for the six months ended September 30, 2020 and 2021. The detailed amounts recorded directly in Equity are as follows: Six months ended 2020 2021 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 579 926 Less: reclassification adjustments 306 (213 ) Total 885 713 Pension liability adjustments: Unrealized gains (losses) 83,994 (2,144 ) Less: reclassification adjustments 321 (3,875 ) Total 84,315 (6,019 ) Own credit risk adjustments: Unrealized gains (losses) (2,351 ) (2,638 ) Less: reclassification adjustments (1,259 ) 219 Total (3,610 ) (2,419 ) Total tax effect before allocation to noncontrolling interests 81,590 (7,725 ) The statutory tax rates were both 30.62% as of September 30, 2020 and 2021. The effective tax rates, 25.15% and 10.34 % for the six months ended September 30, 2020 and 2021, respectively, differed from the statutory tax rates. The difference of the tax rates for the six months ended September 30, 2020 resulted mainly from the effect of noncontrolling interest income of consolidated VIEs. The significant difference of the tax rate for the six months ended September 30, 2021 resulted mainly from 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 was partially offset by an increase in the valuation allowance. At September 30, 2021, the MHFG Group had net operating loss carryforwards totaling ¥788 billion. The total amount of unrecognized tax benefits was ¥4,492 million at September 30, 2021, 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. A portion of unrecognized tax benefits at March 31, 2021 was resolved in the six months period ended September 30, 2021, of which the amount was immaterial. The amount of additional unrecognized tax benefits for the period related to the tax positions taken was also immaterial. The MHFG 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	6 Months Ended
	Sep. 30, 2021
Pension and other employee benefit plans	12. Pension and other employee benefit plans The following table summarizes the components of net periodic benefit cost of the severance indemnities and pension plans of the MHFG Group for the six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Service cost-benefits earned during the period 22,695 16,365 Interest costs on projected benefit obligations 2,931 2,700 Expected return on plan assets (20,073 ) (18,478 ) Amortization of prior service cost (benefits) 205 (2,410 ) Amortization of net actuarial loss (gain) 836 (10,263 ) Special termination benefits 4,981 4,154 Net periodic benefit cost 11,575 (7,932 ) In September 2020, based on various approvals, MHFG and certain domestic subsidiaries communicated to their employees an amendment to the defined benefit pension plans that was effective as of October 1, 2020. In accordance with ASC 715, “Compensation—Retirement Benefits” (“ASC 715”), any change in projected benefit obligations due to a plan amendment is required to be recognized as prior service benefits (cost) as of the amendment date. Accordingly, the MHFG Group recognized ¥73,998 million of prior service benefits for the six months ended September 30, 2020.

Derivative financial instrument

Derivative financial instruments	6 Months Ended
	Sep. 30, 2021
Derivative financial instruments	13. 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 outstan d Fair value Derivative receivables (2) Derivative payables (2) March 31, 2021 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,174,835 — 4,639 — 4,476 Foreign exchange contracts 182,809 — 3,328 — 3,246 Equity-related contracts 7,865 — 531 — 384 Credit-related contracts 10,431 — 94 — 113 Other contracts 413 — 33 — 33 Total 1,376,353 — 8,625 — 8,252 Fair value Derivative receivables (2) Derivative payables (2) September 30, 2021 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,061,161 — 3,404 — 3,245 Foreign exchange contracts 192,620 — 2,487 — 2,383 Equity-related contracts 9,782 — 495 — 328 Credit-related contracts 11,478 — 116 — 136 Other contracts 528 — 63 — 65 Total 1,275,569 — 6,565 — 6,157 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 ¥1,108 billion and ¥764 billion at March 31, 2021, and ¥900 billion and ¥722 billion at September 30, 2021, 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 The following table summarizes gains and losses information related to net investment hedges for the six months ended September 30, 2020 and 2021: Gains (losses) recorded in other for six months ended September 30, 2020 2021 (in millions of yen) Financial instruments hedging foreign exchange risk 1,538 (1,241 ) Total 1,538 (1,241 ) Note: No amount related to the net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the six months ended September 30, 2021. Related to the net investment hedges, gains (losses) of ¥(1,312) million was reclassified from Accumulated other comprehensive income to earnings for the six months ended September 30, 2020. 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 , The following table summarizes gains and losses on derivatives not designated or qualifying as hedges during the six months ended September 30, 2020 and 2021: Gains (losses) recorded in income for six months ended September 30, 2020 2021 (in millions of yen) Interest rate contracts 32,791 20,602 Foreign exchange contracts 26,277 7,407 Equity-related contracts (31,999 ) 33,504 Credit-related contracts (Note) (29,219 ) (15,599 ) Other contracts 26,692 6,875 Total 24,542 52,789 Note: Amounts include the net gains (losses) of ¥(1,221) million and ¥(395) million on the credit derivatives economically managing the cr e 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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 3,687 71 4,150 86 Non-investment 872 17 916 22 Total 4,559 88 5,066 108 Credit protection purchased 5,872 (107 ) 6,412 (128 ) 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, 2021 and September 30, 2021: Maximum payout/Notional amount March 31, 2021 September 30, 2021 (in billions of yen) One year or less 249 230 After one year through five years 4,184 4,662 After five years 126 174 Total 4,559 5,066 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 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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 780 587 Collateral provided to counterparties in the normal course of business 584 436 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 196 151

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Sep. 30, 2021
Commitments and contingencies	14. 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 Group records all guarantees and similar obligations subject to ASC 460, “Guarantees” (“ASC 460”) at fair value in the consolidated balance sheets at the inception of the guarantee. The table below summarizes the maximum potential amount of future payments by type of guarantee at March 31, 2021 and September 30, 2021. 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. March 31, 2021 September 30, 2021 (in billions of yen) Performance guarantees 2,730 2,764 Guarantees on loans 348 448 Guarantees on securities 79 69 Other guarantees 2,390 2,558 Guarantees for the repayment of trust principal 28 25 Liabilities of trust accounts 480 466 Derivative financial instruments 23,933 26,445 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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Investment grade 4,427 4,583 Non-investment 1,120 1,256 Total 5,547 5,839 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 The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Commitments to extend credit (Note) 93,999 87,549 Commercial letters of credit 797 1,028 Total 94,796 88,577 Note: Commitments to extend credit include commitments to invest in securities. Legal proceedings and investigations The MHFG Group is involved in normal consolidated

Variable interest entities and

Variable interest entities and securitizations	6 Months Ended
	Sep. 30, 2021
Text Block [Abstract]
Variable interest entities and securitizations	15. 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 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, 2021 and September 30, 2021: Consolidated VIEs Significant unconsolidated VIEs March 31, 2021 Consolidated assets Total assets Maximum exposure to (in billions of yen) Asset-backed commercial paper/loan programs 2,628 — — Asset-backed securitizations 921 127 48 Investments in securitization products 390 — — Investment funds 2,299 3,219 768 Trust arrangements and other 5,535 — — Total 11,773 3,346 816 Consolidated VIEs Significant unconsolidated VIEs September 30, 2021 Consolidated assets Total assets Maximum exposure to (in billions of yen) Asset-backed commercial paper/loan programs 2,537 — — Asset-backed securitizations 1,198 138 57 Investments in securitization products 394 — — Investment funds 2,146 3,052 716 Trust arrangements and other 5,525 — — Total 11,800 3,190 773 As of March 31, 2021 and September 30, 2021, the noncontrolling interests in consolidated VIEs amounted to ¥464 billion and ¥564 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, 2021 and September 30, 2021: Assets on balance sheets related to unconsolidated VIEs: March 31, 2021 September 30, 2021 (in billions of yen) Trading account assets 127 130 Investments 513 464 Loans 66 68 Total 706 662 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: March 31, 2021 September 30, 2021 (in billions of yen) Payables under securities lending transactions 53 55 Trading account liabilities 2 2 Total 55 57 Maximum exposure to loss (Note) 816 773 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 market in commercial paper issued by the conduits. The MHFG Group typically provides program-wide liquidity and credit support facilities and, in some instances, financing to the VIEs. The MHFG Group has the power to determine which assets will be held by the VIEs and has an obligation to monitor these assets. The Group is also responsible for liability management. In addition, through the liquidity and credit support facilities provided to the VIEs, the Group has the obligation to absorb losses that could potentially be significant to the VIEs. Therefore, the Group consolidates such VIEs. 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 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 consider s off-balance The MHFG Group established certain VIEs to securitize its own mortgage loans. The Group provides servicing for and holds retained subordinated beneficial interests in the securitized mortgage loans. In addition, the Group retains credit exposure in the form of guarantees on these loans. In its role as a servicer, the Group has the power to direct the entity’s activities that most significantly impact the entity’s economic performance by managing defaulted mortgage loans. In addition, through its retained interests and its aforementioned involvement as a guarantor, the Group has the obligation to absorb losses and the right to receive benefits that could potentially be significant to the entity. Therefore, the Group consolidates such VIEs. The MHFG Group started Tender Option Bond (“TOB”) programs in the fiscal year ended March 31, 2020, which are associated with trusts that hold highly-rated, fixed-rate and tax-exempt non-customer non-customer Both types of TOB trusts are deemed to be VIEs because its equity holder does not have decision making rights. The MHFG Group considers that it is a “significant” variable interest when the Group has the residuals as a sponsor and/or provides liquidity and credit support facilities. The Group often commits to provide liquidity to customer TOB trusts and the residual holders of customer TOB trusts are obligated to reimburse the Group for any payment the Group makes under those liquidity and credit support facilities. In non-customer Investments in securitization products The MHFG Group invests in, among other things, va r CLO 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 consolidates 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, as a result from Special Funds-Supplying Operations implemented by the Bank of Japan to facilitate financing in response to COVID-19. 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 sufficient equity to finance their activities; however, the MHFG Group’s investment in the vehicles’ equity is not a variable interest because the investment is not considered to be at risk as the entire amount raised by the vehicles was used to purchase debt instruments issued by the MHFG Group. Because the MHFG Group does not have variable interests in these vehicles, the MHFG Group does not consolidate these entities. Debt instruments issued by the MHFG Group, which are included in Long-term debt, were ¥332 billion and ¥336 billion at March 31, 2021 and September 30, 2021, respectively. 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, “Transfers and Servicing” (“ASC860”) 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 six months ended September 30, 2020 and 2021, 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, 2021 and September 30, 2021. There are certain transactions where transfers of financial assets do not qualify for the aforementioned sales criteria and are accounted for as secured borrowings. These transferred assets continue to be carried on the consolidated balance sheets of the MHFG Group. Such assets are associated with securitization transactions and loan participation transactions, which amounted to ¥176 billion and ¥181 billion as of March 31, 2021, and ¥153 billion and ¥179 billion as of September 30, 2021, respectively. Liabilities associated with securitization and loan participation transactions are presented as Payables under securities lending transactions and Other short-term borrowings or Long-term debt, respectively, on the consolidated balance sheets.

Noninterest income

Noninterest income	6 Months Ended
	Sep. 30, 2021
Noninterest income	16. Noninterest income Details of Noninterest income for the six months ended September 30, 2020 and 2021 are as follows: Six months ended September 30, 2020 2021 (in millions of yen) Fee and commission income: Securities-related business (1) 78,441 89,387 Deposits-related business (1) 7,408 7,569 Lending-related business (2)(4) 79,619 78,053 Remittance business (1) 54,785 54,576 Asset management business (1) 45,948 60,596 Trust-related business (1) 54,425 66,393 Agency business (1) 15,064 18,573 Guarantee-related business (3) 15,560 16,781 Fees for other customer services (1) 77,067 82,988 Total Fee and commission income 428,317 474,916 Foreign exchange gains (losses)—net (3) 22,785 21,708 Trading account gains (losses)—net (2) 257,591 83,255 Investment gains (losses)—net: Debt securities (3) 46 (317 ) Equity securities (3) 266,119 135,070 Equity in earnings (losses) of equity method investees-net (3) 5,788 16,541 Gains on disposal of premises and equipment (3) 6,849 1,988 Other noninterest income (2) (5) 23,715 29,234 Total 1,011,210 762,395 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 17 “Fair value” for further details. Certain Fee and commission income, Trading account gains (losses)-net 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” to the consolidated financial statements in the Group’s most recent Form 20-F. 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 ¥25 billion and ¥29 billion for the six months ended September 30, 2020, respectively, and ¥28 billion and ¥38 billion for the six months ended September 30, 2021, respectively. Trading account gains (losses)—net and Other noninterest income In addition to Fee and commission income, Trading account gains (losses)-net billion for the six months ended September 30, 2020 and 2021, respectively, are within the scope of ASC 606 and accounted for in Trading account gains (losses)-net. 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 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, 2021 and September 30, 2021, the balance of contract assets was not material. Contract liabilities are recognized in unearned income of Other liabilities. As of March 31, 2021 and September 30, 2021, 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, 2021 and September 30, 2021, 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.

Fair value

Fair value	6 Months Ended
	Sep. 30, 2021
Fair value	17. Fair value Fair value measurements ASC 820, “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 six months ended September 30, 2021, there were no significant changes made to the Group’s valuation techniques and related inputs. 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. In the event that certain key 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 severity factors that are developed from market credit spreads and other related market information. Also, the Group records funding valuation adjustments to reflect the impact of funding on uncollateralized over-the-counter 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 such securities, the Group firstly considers recent market transactions of identical securities, if applicable. Thereafter, the Group uses commonly accepted valuation techniques such as earnings multiples based on comparable public securities. 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, 2021 and September 30, 2021, including those for which the MHFG Group has elected the fair value option, are summarized below: March 31, 2021 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,923 11 — 1,934 Japanese local government bonds — 120 — 120 U.S. Treasury bonds and federal agency securities 3,544 604 — 4,148 Other foreign government bonds 775 500 — 1,275 Agency mortgage-backed securities — 4,727 — 4,727 Residential mortgage-backed securities — — 9 9 Certificates of deposit and commercial paper — 1,204 — 1,204 Corporate bonds and other (2) 34 1,638 1,033 2,705 Equity securities 1,220 326 29 1,575 Trading securities measured at net asset value (3) 431 Derivative financial instruments: Interest rate contracts 63 4,564 12 4,639 Foreign exchange contracts — 3,304 24 3,328 Equity-related contracts 170 339 22 531 Credit-related contracts — 91 3 94 Other contracts 10 6 17 33 Available-for-sale Japanese government bonds 20,598 323 — 20,921 Japanese local government bonds — 463 — 463 U.S. Treasury bonds and federal agency securities 911 — — 911 Other foreign government bonds 535 972 — 1,507 Agency mortgage-backed securities — 521 — 521 Residential mortgage-backed securities — 48 23 71 Commercial mortgage-backed securities — — 716 716 Japanese corporate bonds and other debt securities — 1,539 365 1,904 Foreign corporate bonds and other debt securities — 707 132 839 Equity securities: Equity securities with readily determinable fair values 3,375 104 — 3,479 Equity securities measured at net asset value (3) 121 Other investments 2 — 53 55 Total assets measured at fair value on a recurring basis 33,160 22,111 2,438 58,261 Liabilities: Trading securities sold, not yet purchased 2,138 488 — 2,626 Derivative financial instruments: Interest rate contracts 64 4,408 4 4,476 Foreign exchange contracts — 3,245 1 3,246 Equity-related contracts 224 117 43 384 Credit-related contracts — 112 1 113 Other contracts 7 9 17 33 Long-term debt (4) — 1,990 713 2,703 Total liabilities measured at fair value on a recurring basis 2,433 10,369 779 13,581 September 30, 2021 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 2,612 9 — 2,621 Japanese local government bonds — 74 — 74 U.S. Treasury bonds and federal agency securities 4,900 770 — 5,670 Other foreign government bonds 760 527 — 1,287 Agency mortgage-backed securities — 4,715 — 4,715 Residential mortgage-backed securities — — 8 8 Certificates of deposit and commercial paper — 1,121 — 1,121 Corporate bonds and other (2) 58 1,780 826 2,664 Equity securities 1,961 227 30 2,218 Trading securities measured at net asset value (3) 374 Derivative financial instruments: Interest rate contracts 31 3,363 10 3,404 Foreign exchange contracts — 2,464 23 2,487 Equity-related contracts 189 283 23 495 Credit-related contracts — 113 3 116 Other contracts 26 4 33 63 Available-for-sale Japanese government bonds 18,807 196 — 19,003 Japanese local government bonds — 495 — 495 U.S. Treasury bonds and federal agency securities 1,074 — — 1,074 Other foreign government bonds 444 887 — 1,331 Agency mortgage-backed securities — 599 — 599 Residential mortgage-backed securities — 44 20 64 Commercial mortgage-backed securities — 1 766 767 Japanese corporate bonds and other debt securities — 1,637 347 1,984 Foreign corporate bonds and other debt securities — 764 117 881 Equity securities: Equity securities with readily determinable fair values 3,717 106 — 3,823 Equity securities measured at net asset value (3) 160 Other investments 3 — 53 56 Total assets measured at fair value on a recurring basis 34,582 20,179 2,259 57,554 Liabilities: Trading securities sold, not yet purchased 2,172 805 — 2,977 Derivative financial instruments: Interest rate contracts 30 3,210 5 3,245 Foreign exchange contracts — 2,382 1 2,383 Equity-related contracts 167 99 62 328 Credit-related contracts — 134 2 136 Other contracts 18 15 32 65 Long-term debt (4) — 2,111 752 2,863 Total liabilities measured at fair value on a recurring basis 2,387 8,756 854 11,997 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, 2021 and September 30, 2021 were ¥55 billion and ¥54 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 six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 April 1, 2020 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments September 30, 2020 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 10 — (2) — — — — — — (1 ) 9 — Corporate bonds and other 1,115 18 (2) — — (1 ) 189 (113 ) — (123 ) 1,085 18 Equity securities 30 (2 ) (2) — — — 2 — — — 30 (1 ) Derivative financial instruments, net (1) Interest rate contracts (5 ) (3 ) (2) — — — — — — 5 (3 ) 1 Foreign exchange contracts 16 4 (2) — — — — — — (1 ) 19 5 Equity-related contracts (17 ) 4 (2) — — — — — — 2 (11 ) 3 Credit-related contracts (2 ) 3 (2) — 1 1 — — — (2 ) 1 1 Other contracts 1 — (2) — — — — — — — 1 — Available-for-sale Residential mortgage-backed securities 31 — (3) — (4) — — — — — (4 ) 27 — Commercial mortgage-backed securities 615 — (3) 1 (4) — — 78 (51 ) — (2 ) 641 — Japanese corporate bonds and other debt securities 157 (7 ) (3) 8 (4) — — 344 — — (11 ) 491 — Foreign corporate bonds and other debt securities 174 1 (3) 8 (4) — — 31 — — (36 ) 178 — Other investments 39 (1 ) (3) — — — 38 (1 ) — (19 ) 56 (1 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — — 20 — — 20 — Long-term debt 621 (37 ) (5) (8 ) (4) 19 (35 ) — — 108 (120 ) 638 (27 ) Six months ended September 30, 2021 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 September 30, 2021 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed 9 — (2) — — — — — — (1 ) 8 — Corporate bonds and other 1,033 4 (2) — — (1 ) 232 (144 ) — (298 ) 826 5 Equity securities 29 1 (2) — — — — — — — 30 1 Derivative financial instruments, net (1) Interest rate contracts 8 (5 ) (2) — — — — — — 2 5 (5 ) Foreign exchange contracts 23 (1 ) (2) — — — — — — — 22 (2 ) Equity-related contracts (21 ) (14 ) (2) — — — — — — (4 ) (39 ) (22 ) Credit-related contracts 2 (1 ) (2) — (1 ) — — — — 1 1 1 Other contracts — 1 (2) — — — — — — — 1 — Available-for-sale Residential mortgage-backed 23 — (3) — (4) — — — — — (3 ) 20 — Commercial mortgage-backed 716 — (3) — (4) — — 63 (6 ) — (7 ) 766 — Japanese corporate bonds and other 365 2 (3) — (4) — — 8 — — (28 ) 347 2 Foreign corporate bonds and other 132 — (3) (3 ) (4) — — 19 — — (31 ) 117 — Other investments 53 (1 ) (3) — — — 34 (1 ) — (32 ) 53 (2 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — (1 ) 1 — — — — Long-term debt 713 6 (5) (5 ) (4) 1 (1 ) — — 256 (216 ) 752 9 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 OCI 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 September 30, 2020 and 2021. The amounts of unrealized gains (losses) in OCI are related to Available-for-sale securities and Long-term debt, which were ¥7 billion and ¥(8) billion, respectively, at September 30, 2020, and ¥nil billion and billion, respectively, at September 30, 2021. Transfers During the six months ended September 30, 2020, the transfers into Level 3 included ¥1 billion of net Derivative assets and ¥19 billion of Long-term debt. Transfers into Level 3 for net Derivative assets were primarily due to changes in the observability of the inputs used to measure fair value of certain credit-related derivatives. Transfers into Level 3 for Long-term debt were primarily due to changes in the observability of the default rate when valuing certain structured notes. During the six months ended September 30, 2020, the transfers out of Level 3 included ¥1 billion of Trading securities, ¥1 billion of net Derivative liabilities and ¥35 billion of Long-term debt. Transfers out of Level 3 for Trading securities were primarily due to increased price transparency for certain Japanese corporate bonds. Transfers out of Level 3 for net Derivative liabilities were primarily due to changes in the observability of the inputs used to measure fair value of certain credit-related derivatives. Transfers out of Level 3 for Long-term debt were primarily due to changes in the observability of the default rate when valuing certain structured notes. During the six months ended September 30, 2021, the transfers into Level 3 included ¥1 billion of net Derivative liabilities and ¥1 billion of Long-term debt. Transfers into Level 3 for net Derivative liabilities were primarily due to changes in the observability of the inputs used to measure fair value of certain credit-related derivatives. Transfers into Level 3 for Long-term debt were primarily due to changes in the observability of the default rate when valuing certain structured notes. During the six months ended September 30, 2021, the transfers out of Level 3 included ¥1 billion of Trading securities and ¥1 billion of Long-term debt. 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 Long-term debt were primarily due to changes in the observability of the default rate when valuing certain structured notes . Quantitative information about Level 3 fair value measurements The following table presents information about significant unobservable inputs related to the MHFG Group’s material classes of Level 3 assets and liabilities at March 31, 2021 and September 30, 2021: March 31, 2021 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 32 Discounted cash flow Prepayment rate Default rate Recovery rate Discount margin 2% - 17% 0% - 1% 100% - 100% 28bps - 170bps 7% Commercial mortgage-backed securities 716 Discounted cash flow Discount margin 5bps - 210bps 22bps Corporate bonds and other debt securities 1,530 Discounted cash flow Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 10% - 1% - 24% 10% - 68% 45bps - 143bps 4bps - 507bps 18% 2% 66% 115bps 284bps Derivative financial instruments, net: Interest rate contracts 8 Internal valuation model (3) IR – IR correlation 35% - 100% 76% Foreign exchange contracts 23 Internal valuation model (3) FX – IR correlation FX – FX correlation 23% - 50% 43% - 30% 54% Equity-related contracts (21 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25% - 25% 0% - 100% 8% - 71% 25% 88% 41% Credit-related contracts 2 Internal valuation model (3) Default rate Credit correlation 0% - 40% - 100% 1% 66% Other contracts — Internal valuation model (3) Commodity volatility 0% - 33% Long-term debt 713 Internal valuation model (3) IR – IR correlation FX – IR correlation FX – FX correlation Equity – IR correlation Equity – FX correlation Equity correlation Equity volatility Default rate Credit correlation 49% - 100% 23% - 50% 43% - 65% 25% - -33% - 50% 0% - 100% 8% - 71% 0% - 17% - 100% 78% 36% 54% 25% 0% 88% 29% 1% 68% September 30, 2021 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 28 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 1% - 17% 0% - 1% 100% - 100% 28bps - 170bps 6% 0% 100% 50bps Commercial mortgage-backed securities 766 Discounted cash flow Price-based Discount margin 6bps - 726bps 23bps Corporate bonds and other debt securities 1,290 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 22% - 24% 0% - 30 10% - 68% 25bps - 143bps 4bps - 502bps 24% 2% 65% 109bps 387bps Derivative financial instruments, net: Interest rate contracts 5 Internal valuation model (3) IR – IR correlation 23% - 100% 75% Foreign exchange contracts 22 Internal valuation model (3) FX – IR correlation FX – FX correlation 24% - 51% 41% - 65% 31% 53% Equity-related contracts (39 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25% - 25% 7% - 100% 7% - 101% 25% 89% 45% Credit-related contracts 1 Internal valuation model (3) Default rate Credit correlation 0% - 5% 41% - 100% 1% 67% Other contracts 1 Internal valuation model (3) Commodity volatility 0% - 41% 33% Long-term debt 752 Internal valuation model (3) IR – IR correlation FX – IR correlation FX – FX correlation Equity – IR correlation Equity – FX correlation Equity correlation Equity volatility Default rate Credit correlation 23% - 100% 24% - 51% 41% - 65% 25% - 25% -18% - 7% - 100% 7% - 101% 0% - 6% 17% - 100% 75% 39% 53% 25% 0% 89% 31% 1% 67% 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) This input represents the counterparty default rate derived from the MHFG Group’s own internal credit analyses. (5) 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. 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, 2021 and September 30, 2021: March 31, 2021 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 85 — 3 82 167 Loans held-for-sale 22 — 21 1 23 Equity securities (without readily determinable fair values) 3 — — 3 4 Premises and equipment-net — — — — 7 Other assets 24 — — 24 34 Total assets measured at fair value on a nonrecurring basis 134 — 24 110 235 September 30, 2021 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 57 — — 57 102 Loans held-for-sale 21 — 11 10 22 Equity securities (without readily determinable fair values) 24 — 16 8 10 Other investments 3 3 — — 5 Total assets measured at fair value on a nonrecurring basis 105 3 27 75 139 Note: The fair values may not be current as of the dates indicated, but rather as of the da t 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 Equity securities (without readily determinable fair values) in the table above consist of non-marketable non-marketable 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. There were no other investments measured at fair value on a nonrecurring basis as of March 31, 2021. Premises and equipment—net and Other assets in the table above have been impaired and written down to fair value. There were no premises and equipment—net and other assets measured at fair value on a nonrecurring basis as of September 30, 2021. 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 ¥14 billion and ¥11 billion at March 31, 2021 and September 30, 2021, respectively. The net unrealized gains (losses) resulting from changes in fair values of these notes recorded in Other noninterest income (expenses) were of ¥17 billion and ¥(30) billion for the six months ended September 30, 2020 and 2021, 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

Offsetting of financial assets

Offsetting of financial assets and financial liabilities	6 Months Ended
	Sep. 30, 2021
Offsetting of financial assets and financial liabilities	18. 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, 2021 and September 30, 2021. 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) March 31, 2021 Assets (1) Derivatives 8,625 — 8,625 (5) (6,323 ) (588 ) 1,714 Receivables under resale agreements 11,623 — 11,623 (6) (10,478 ) — 1,145 Receivables under securities borrowing transactions 2,694 — 2,694 (7) (2,621 ) — 73 Total 22,942 — 22,942 (19,422 ) (588 ) 2,932 Liabilities (1) Derivatives 8,252 — 8,252 (5) (6,033 ) (933 ) 1,286 Payables under repurchase agreements 18,607 — 18,607 (6) (17,979 ) — 628 Payables under securities lending transactions 1,208 — 1,208 (7) (953 ) — 255 Total 28,067 — 28,067 (24,965 ) (933 ) 2,169 September 30, 2021 Assets (1) Derivatives 6,565 — 6,565 (5) (4,611 ) (557 ) 1,397 Receivables under resale agreements 16,933 — 16,933 (6) (15,890 ) — 1,043 Receivables under securities borrowing transactions 2,408 — 2,408 (7) (2,355 ) — 53 Total 25,906 — 25,906 (22,856 ) (557 ) 2,493 Liabilities (1) Derivatives 6,157 — 6,157 (5) (4,348 ) (748 ) 1,061 Payables under repurchase agreements 22,278 — 22,278 (6) (21,471 ) — 807 Payables under securities lending transactions 1,441 — 1,441 (7) (1,221 ) — 220 Total 29,876 — 29,876 (27,040 ) (748 ) 2,088 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 ¥8,168 billion and ¥7,652 billion, respectively, at March 31, 2021, and ¥6,256 billion and ¥5,808 billion, respectively, at September 30, 2021. (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 ¥10,551 billion and ¥18,321 billion, respectively, at March 31, 2021, and ¥15,957 billion and ¥21,817 billion, respectively, at September 30, 2021. (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 ¥2,694 billion and ¥958 billion, respectively, at March 31, 2021, and ¥2,408 billion and ¥1,229 billion, respectively, at September 30, 2021.

Repurchase agreements and secur

Repurchase agreements and securities lending transactions accounted for as secured borrowings	6 Months Ended
	Sep. 30, 2021
Repurchase agreements and securities lending transactions accounted for as secured borrowings	19. 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, 2021 and September 30, 2021: Overnight and continuous Up to 30 days 31-90 days Greater than 90 days Total (in billions of yen) March 31, 2021 Repurchase agreements 9,459 3,586 4,315 1,247 18,607 Securities lending transactions 943 15 — 250 1,208 Total 10,402 3,601 4,315 1,497 19,815 September 30, 2021 Repurchase agreements 14,303 3,151 3,082 1,742 22,278 Securities lending transactions 1,093 136 12 200 1,441 Total 15,396 3,287 3,094 1,942 23,719 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, 2021 and September 30, 2021: Repurchase agreements Securities lending transactions (in billions of yen) March 31, 2021 Japanese government bonds and Japanese local government bonds 1,787 352 Foreign government bonds and foreign agency mortgage-backed securities 15,917 131 Commercial paper and corporate bonds 284 57 Equity securities 544 654 Other 75 14 Total 18,607 1,208 September 30, 2021 Japanese government bonds and Japanese local government bonds 2,767 234 Foreign government bonds and foreign agency mortgage-backed securities 18,339 153 Commercial paper and corporate bonds 264 52 Equity securities 838 989 Other 70 13 Total 22,278 1,441 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. The amounts or composition of assets pledged as collateral for borrowings and for other purposes have not changed significantly since March 31, 2021. See Note 8 “Pledged assets and collateral” to the consolidated financial statements in the MHFG Group’s annual report on Form 20-F

Business segment information

Business segment information	6 Months Ended
	Sep. 30, 2021
Business segment information	20. 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 MHFG (Consolidated) Six months ended September 30, 2020 (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) 314.2 226.6 226.0 293.0 23.8 9.7 1,093.3 General and administrative expenses (3) 313.5 104.0 125.2 105.3 15.7 15.6 679.3 Equity in earnings (losses) of equity method investees—net 3.5 2.4 5.9 — 0.4 (0.7 ) 11.5 Amortization of goodwill and others 1.1 0.1 0.2 0.4 3.8 0.5 6.1 Net business profits (losses) (4) 3.1 124.9 106.5 187.3 4.7 (7.1 ) 419.4 Fixed assets (5) 516.2 195.7 162.8 95.6 — 751.0 1,721.3 MHFG (Consolidated) Six months ended September 30, 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) 345.9 230.1 250.0 253.7 29.0 21.9 1,130.6 General and administrative expenses (3) 311.3 99.3 126.2 107.5 16.2 20.4 680.9 Equity in earnings (losses) of equity method investees—net 5.5 2.3 7.4 — 0.8 0.5 16.5 Amortization of goodwill and others 1.1 — 0.2 0.4 3.6 0.5 5.8 Net business profits (losses) (4) 39.0 133.1 131.0 145.8 10.0 1.5 460.4 Fixed assets (5) 538.6 182.5 166.7 96.3 — 738.2 1,722.3 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 investees-net (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 • 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 six months ended September 30, 2020 and 2021 presented above to income before income tax expense shown on the consolidated statements of income and a reconciliation of “Fixed assets” at September 30, 2020 and 2021 to the total amount of Premises and equipment-net, right-of-use Six months ended September 30, 2020 2021 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 419.4 460.4 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated 4.1 19.2 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (84.8 ) (59.9 ) Gains on reversal of reserves for possible losses on loans, and others 3.6 10.2 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others (50.5 ) (6.9 ) Net extraordinary gains (losses) 65.8 47.3 Others (24.2 ) (23.7 ) Income before income tax expense under Japanese GAAP 333.4 446.6 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (12.9 ) (47.9 ) Investments 285.4 13.8 Loans (10.8 ) 2.2 Allowances for credit losses 35.8 5.0 Premises and equipment (37.1 ) (34.9 ) Land revaluation 2.7 1.6 Business combinations (4.3 ) 3.4 Pension liabilities (84.5 ) (63.9 ) Consolidation of variable interest entities 36.6 51.1 Foreign currency translation (0.2 ) 2.4 Others 3.7 3.8 Income before income tax expense under U.S. GAAP 547.8 383.2 As of September 30, 2020 2021 (in billions of yen) Fixed assets 1,721.3 1,722.3 U.S. GAAP adjustments (Note) 818.4 763.6 Premises and equipment-net, right-of-use 2,539.7 2,485.9 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from right-of-use

Basis of presentation (Policies

Basis of presentation (Policies)	6 Months Ended
	Sep. 30, 2021
Basis of presentation	1. 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 20 “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 interim financial reporting period ends on September 30. Certain of MHFG’s subsidiaries have different interim financial reporting periods than September 30. For those subsidiaries with interim financial reporting periods within three months of MHFG’s interim financial reporting period, the effect of intervening events that materially affect the financial position or results of operations through the date of each of the periods presented in the MHFG’s consolidated financial statements have 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. On October 1, 2020, a 1-for-10 The unaudited interim consolidated financial statements should be read in conjunction with the audited financial statements and related notes included in the MHFG Group’s most recent annual report on Form 20-F for the fiscal year ended March 31, 2021. Certain financial information that is normally included in annual financial statements prepared in accordance with U.S. GAAP, but is not required for interim reporting purposes, has been condensed or omitted. The financial statements reflect all normal and recurring adjustments that are, in the opinion of management, necessary for a fair presentation of the results for the interim periods.
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 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 pandemics, such as COVID-19,
Financial instruments—current expected credit losses ("CECL")	Financial instruments—current expected credit losses (“CECL”) The adoption of this guidance established a single allowance framework for all financial assets measured at amortized cost and certain off-balance-sheet losses available-for-sale further impact
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 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 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 ratings 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 consistent to what is used in the MHFG Group’s stress testing and 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 includes the allowance for groups of loans which were collectively evaluated for expected credit losses, in addition to 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 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 troubled debt restructuring (“TDR”) loans 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. Considering internal and external factors affecting the credit quality of the portfolio, the Group incorporated the estimated impact of COVID-19
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 assesses the expected loss amounts for commitments to invest in securities and commitments to extend credit, considering the probability of drawdowns. The allowance is recorded in Other liabilities. Net changes in the allowance for credit losses on 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 impaired Available-for-sale available-for-sale available-for-sale available-for-sale available-for-sale .

Investments (Tables)

Investments (Tables)	6 Months Ended
	Sep. 30, 2021
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 cost (4)(5) Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) March 31, 2021 Available-for-sale Debt securities: Japanese government bonds 20,953,200 1,945 34,562 20,920,583 Japanese local government bonds 463,673 544 658 463,559 U.S. Treasury bonds and federal agency securities 906,499 4,440 46 910,893 Other foreign government bonds 1,505,770 1,975 209 1,507,536 Agency mortgage-backed securities (1) 512,720 8,746 687 520,779 Residential mortgage-backed securities 70,111 761 188 70,684 Commercial mortgage-backed securities 709,938 6,196 39 716,095 Japanese corporate bonds and other debt securities 1,897,117 10,537 3,574 1,904,080 Foreign corporate bonds and other debt securities (2) 837,675 2,577 1,426 838,826 Total 27,856,703 37,721 41,389 27,853,035 Held-to-maturity Debt securities: Japanese government bonds 479,959 9,555 — 489,514 Agency mortgage-backed securities (3) 407,190 10,178 3,273 414,095 Total 887,149 19,733 3,273 903,609 September 30, 2021 Available-for-sale Debt securities: Japanese government bonds 19,029,022 498 26,477 19,003,043 Japanese local government bonds 494,716 713 486 494,943 U.S. Treasury bonds and federal agency securities 1,070,555 3,269 69 1,073,755 Other foreign government bonds 1,331,043 783 889 1,330,937 Agency mortgage-backed securities (1) 591,778 8,467 853 599,392 Residential mortgage-backed securities 63,273 706 137 63,842 Commercial mortgage-backed securities 760,959 6,182 224 766,917 Japanese corporate bonds and other debt securities 1,977,235 9,962 2,774 1,984,423 Foreign corporate bonds and other debt securities (2) 880,838 1,601 979 881,460 Total 26,199,419 32,181 32,888 26,198,712 Held-to-maturity Debt securities: Japanese government bonds 479,970 7,437 — 487,407 Agency mortgage-backed securities (3) 915,678 7,203 6,705 916,176 Total 1,395,648 14,640 6,705 1,403,583 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 ¥520,746 million and ¥33 million, respectively, at March 31, 2021, and ¥599,359 million and ¥33 million, respectively, at September 30, 2021. 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 ¥ (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 (5) Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 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 11,112,193 6,466,555 1,182,864 267,410 19,029,022 Japanese local government bonds 41,016 241,693 204,491 7,516 494,716 U.S. Treasury bonds and federal agency securities 422,693 647,862 — — 1,070,555 Other foreign government bonds 917,929 410,999 1,059 1,056 1,331,043 Agency mortgage-backed securities — — — 591,778 591,778 Residential mortgage-backed securities — — — 63,273 63,273 Commercial mortgage-backed securities 34,244 338,785 385,530 2,400 760,959 Japanese corporate bonds and other debt securities 103,494 996,194 333,038 544,509 1,977,235 Foreign corporate bonds and other debt securities 515,116 292,020 68,649 5,053 880,838 Total 13,146,685 9,394,108 2,175,631 1,482,995 26,199,419 Held-to-maturity Debt securities: Japanese government bonds — 479,970 — — 479,970 Agency mortgage-backed securities — — — 915,678 915,678 Total — 479,970 — 915,678 1,395,648 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 11,111,775 6,460,865 1,166,584 263,819 19,003,043 Japanese local government bonds 41,027 241,790 204,570 7,556 494,943 U.S. Treasury bonds and federal agency securities 423,719 650,036 — — 1,073,755 Other foreign government bonds 917,972 410,850 1,059 1,056 1,330,937 Agency mortgage-backed securities — — — 599,392 599,392 Residential mortgage-backed securities — — — 63,842 63,842 Commercial mortgage-backed securities 34,263 340,915 389,302 2,437 766,917 Japanese corporate bonds and other debt securities 103,477 996,501 332,963 551,482 1,984,423 Foreign corporate bonds and other debt securities 515,240 292,089 69,078 5,053 881,460 Total 13,147,473 9,393,046 2,163,556 1,494,637 26,198,712 Held-to-maturity Debt securities: Japanese government bonds — 487,407 — — 487,407 Agency mortgage-backed securities — — — 916,176 916,176 Total — 487,407 — 916,176 1,403,583
Gross Unrealized Losses and Fair Value of Available-for-Sale 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) March 31, 2021 Available-for-sale Debt securities: Japanese government bonds 9,998,772 1,924 4,058,718 32,638 14,057,490 34,562 Japanese local government bonds 125,058 323 130,384 335 255,442 658 U.S. Treasury bonds and federal agency securities 38,625 46 — — 38,625 46 Other foreign government bonds 576,415 209 — — 576,415 209 Agency mortgage-backed securities (Note) 70,088 120 36,989 567 107,077 687 Residential mortgage-backed securities 9,270 52 11,435 136 20,705 188 Commercial mortgage-backed securities 12,530 6 10,351 33 22,881 39 Japanese corporate bonds and other debt securities 278,698 953 843,026 2,621 1,121,724 3,574 Foreign corporate bonds and other debt securities 233,405 1,426 — — 233,405 1,426 Total 11,342,861 5,059 5,090,903 36,330 16,433,764 41,389 September 30, 2021 Available-for-sale Debt securities: Japanese government bonds 13,200,228 4,197 1,977,981 22,280 15,178,209 26,477 Japanese local government bonds 93,142 137 147,795 349 240,937 486 U.S. Treasury bonds and federal agency securities 39,048 69 — — 39,048 69 Other foreign government bonds 622,377 856 66,431 33 688,808 889 Agency mortgage-backed securities (Note) 81,466 253 61,604 600 143,070 853 Residential mortgage-backed securities 6,862 28 12,074 109 18,936 137 Commercial mortgage-backed securities 42,905 184 9,786 40 52,691 224 Japanese corporate bonds and other debt securities 488,973 830 690,315 1,944 1,179,288 2,774 Foreign corporate bonds and other debt securities 266,866 328 60,191 651 327,057 979 Total 14,841,867 6,882 3,026,177 26,006 17,868,044 32,888 Note: Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥107,077 million at March 31, 2021, and ¥143,070 million at September 30, 2021. 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 Six months ended September 30, 2020 2021 (in millions of yen) Gross realized gains 5,101 4,687 Gross realized losses (3,694 ) (3,925 ) Net realized gains (losses) on sales of available-for-sale 1,407 762
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 six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Net gains (losses) recognized during the period on equity securities 266,119 135,070 Less: Net gains (losses) recognized during the period on equity securities sold during the period 34,985 29,552 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period 231,134 105,518
Summary of 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 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Carrying amounts at the end of the period 186,146 208,869 Downward adjustments and impairments 5,087 6,580 Upward adjustments 9,216 24,126
Summary of Downward Adjustments and Impairments and Upward Adjustments	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. Six months ended September 30, 2020 2021 (in millions of yen) Downward adjustments and impairments 1,411 1,704 Upward adjustments 34 14,950
Summary of Composition of Other Investments	The following table summarizes the composition of Other investments at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Equity method investments 460,025 493,573 Investments held by consolidated investment companies and other 55,321 60,728 Total 515,346 554,301

Loans (Tables)

Loans (Tables)	6 Months Ended
	Sep. 30, 2021
Loans Outstanding by Domicile and Industry of Borrower	The table below presents loans outstanding by domicile and industry of borrower at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Domestic: Manufacturing 11,010,644 10,569,793 Construction and real estate 10,492,162 10,664,028 Services 6,406,710 6,002,667 Wholesale and retail 5,357,287 5,432,264 Transportation and communications 3,885,807 3,912,609 Banks and other financial institutions (1) 4,695,677 4,231,331 Government and public institutions 1,898,137 1,596,867 Other industries (2) 5,918,260 5,997,987 Individuals: Mortgage loans 8,193,398 8,039,138 Other 790,184 758,680 Total domestic 58,648,266 57,205,364 Foreign: Commercial and industrial (3) 19,454,623 19,368,406 Banks and other financial institutions (4) 10,448,778 10,561,219 Government and public institutions 177,385 192,055 Other 18,843 24,362 Total foreign 30,099,629 30,146,042 Total 88,747,895 87,351,406 Less: Unearned income and deferred loan fees-net 167,028 165,636 Total loans before allowance for credit losses on loans 88,580,867 87,185,770 Notes: (1) Banks and other financial institutions of domestic includes mainly banks, securities companies, insurance companies and credit card companies. (2) Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs. (3) Commercial and industrial of foreign includes ¥221,908 million and ¥221,144 million of lease receivables that are receivables arising from direct financing leasing at March 31, 2021 and September 30, 2021, respectively. (4) Banks and other financial institutions of foreign includes mainly banks and financial services companies.
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, 2021 and September 30, 2021: March 31, 2021 Term loans by origination year Revolving Loans Total 2020 2019 2018 2017 2016 Prior to 2016 (in millions of yen) Domestic: Corporate: Large companies: Normal obligors 14,351,596 6,173,182 6,884,219 2,384,565 2,105,541 2,256,613 6,819,851 40,975,567 Watch obligors excluding special attention obligors 151,406 86,390 86,199 61,785 40,907 35,681 128,363 590,731 Nonaccrual loans 219,111 196,945 38,490 129,066 28,650 9,547 194,607 816,416 Small and medium-sized Normal obligors 633,438 463,744 397,656 224,791 205,687 502,707 518,612 2,946,635 Watch obligors excluding special attention obligors 62,300 24,245 30,007 13,547 13,536 24,430 29,041 197,106 Nonaccrual loans 78,238 10,794 7,341 5,168 3,154 8,852 28,853 142,400 Retail: Housing Loan: Normal obligors 785,194 588,599 588,535 600,179 741,969 4,599,546 — 7,904,022 Watch obligors excluding special attention obligors 2,041 1,075 1,566 1,343 2,127 39,046 — 47,198 Nonaccrual loans 20,706 2,268 1,399 1,421 1,640 35,135 — 62,569 Others: Normal obligors 431,277 154,675 127,379 88,649 85,042 317,237 526,703 1,730,962 Watch obligors excluding special attention obligors 50,212 14,288 10,450 5,888 3,713 5,796 10,545 100,892 Nonaccrual loans 32,594 2,086 1,145 901 837 8,780 12,557 58,900 Sovereign: Normal obligors 1,466,468 80,260 128,702 71,943 75,389 389,777 12,615 2,225,154 Watch obligors excluding special attention obligors 4,312 3,594 2,164 635 31 — — 10,736 Nonaccrual loans — — — — — — — — Banks and other financial institutions (4): Normal obligors 51,874 135,135 241,418 24,097 84,244 60,281 162,622 759,671 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 18,340,767 7,937,280 8,546,670 3,613,978 3,392,467 8,293,428 8,444,369 58,568,959 Foreign: Corporate: Normal obligors 12,813,813 4,614,310 2,558,432 922,526 655,823 1,143,658 4,501,155 27,209,717 Watch obligors excluding special attention obligors 196,054 36,915 72,529 54,514 894 25,009 127,553 513,468 Nonaccrual loans 61,657 29,657 12,547 3,034 4,417 17,394 14,580 143,286 Retail: Normal obligors 2,100 2,342 1,468 1,034 1,074 1,401 18 9,437 Watch obligors excluding special attention obligors — — — 14 — 13 — 27 Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 96,177 78,727 26,569 157,256 — 4,474 69,320 432,523 Watch obligors excluding special attention obligors — — — — — 20,118 — 20,118 Nonaccrual loans — 710 — — — — — 710 Banks and other financial institutions (5) Normal obligors 1,030,080 317,635 275,695 18,272 1,497 3,105 25,145 1,671,429 Watch obligors excluding special attention obligors 6,341 — 78 — 4,774 — — 11,193 Nonaccrual loans — — — — — — — — Total foreign 14,206,222 5,080,296 2,947,318 1,156,650 668,479 1,215,172 4,737,771 30,011,908 Total 32,546,989 13,017,576 11,493,988 4,770,628 4,060,946 9,508,600 13,182,140 88,580,867 September 30, 2021 Term loans by origination year Revolving Total 2021 2020 2019 2018 2017 Prior to 2017 (in millions of yen) Domestic: Corporate: Large companies: Normal obligors 8,189,714 8,020,885 5,614,210 6,241,858 2,078,317 3,590,252 6,537,575 40,272,811 Watch obligors excluding special attention obligors 81,285 96,286 84,448 81,316 47,014 64,902 140,816 596,067 Nonaccrual loans 84,652 121,840 198,406 38,431 136,798 54,315 199,683 834,125 Small and medium-sized Normal obligors 308,157 496,873 431,411 339,670 203,267 563,176 521,714 2,864,268 Watch obligors excluding special attention obligors 33,846 36,441 31,820 27,171 13,205 34,406 30,506 207,395 Nonaccrual loans 62,960 22,583 8,509 3,328 2,391 9,516 31,481 140,768 Retail: Housing Loan: Normal obligors 447,717 614,629 550,698 556,355 571,772 5,039,717 — 7,780,888 Watch obligors excluding special attention obligors 481 1,894 845 1,783 1,142 40,431 — 46,576 Nonaccrual loans 10,775 7,452 1,175 1,349 1,100 33,144 — 54,995 Others: Normal obligors 130,034 319,234 131,507 107,610 73,837 353,742 507,467 1,623,431 Watch obligors excluding special attention obligors 18,393 41,274 13,092 9,820 5,015 8,469 9,915 105,978 Nonaccrual loans 28,342 9,376 1,800 1,062 899 8,949 12,973 63,401 Sovereign: Normal obligors 844,284 266,527 85,704 125,215 72,379 425,654 1,100 1,820,863 Watch obligors excluding special attention obligors 951 5,118 1,145 576 161 — — 7,951 Nonaccrual loans — — — — — — — — Banks and other financial institutions (4) Normal obligors 48,602 24,845 132,967 221,456 — 144,044 139,047 710,961 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — — — — — — — Total domestic 10,290,193 10,085,257 7,287,737 7,757,000 3,207,297 10,370,717 8,132,277 57,130,478 Foreign: Corporate: Normal obligors 9,887,658 4,993,722 4,023,459 1,961,077 730,828 1,347,278 4,614,140 27,558,162 Watch obligors excluding special attention obligors 149,058 106,849 40,203 44,477 19,720 16,717 110,385 487,409 Nonaccrual loans 15,194 17,043 36,032 7,935 765 20,188 8,714 105,871 Retail: Normal obligors 1,130 1,569 1,978 1,199 522 3,510 17 9,925 Watch obligors excluding special attention obligors — — 40 — — 14 — 54 Nonaccrual loans — — — — — — — — Sovereign: Normal obligors 65,240 44,751 53,723 24,142 158,689 3,532 61,176 411,253 Watch obligors excluding special attention obligors — — — — — — — — Nonaccrual loans — — 653 — — — — 653 Banks and other financial institutions (5) Normal obligors 636,823 345,528 197,395 249,809 16,127 1,506 28,627 1,475,815 Watch obligors excluding special attention obligors — 5,390 152 608 — — — 6,150 Nonaccrual loans — — — — — — — — Total foreign 10,755,103 5,514,852 4,353,635 2,289,247 926,651 1,392,745 4,823,059 30,055,292 Total 21,045,296 15,600,109 11,641,372 10,046,247 4,133,948 11,763,462 12,955,336 87,185,770 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 six months ended September 30, 2021. (4) Banks and other financial institutions of domestic includes mainly banks and securities companies (5) Banks and other financial institutions of foreign includes mainly banks.
Impaired Loans Information	The table below presents nonaccrual loans information at March 31, 2021 and September 30, 2021: Amortized cost Nonaccrual loans with an allowance Nonaccrual loans without an allowance Total nonaccrual loans Interest income recognized (in millions of yen) March 31, 2021 Domestic: Corporate: Large companies 800,329 16,087 816,416 13,050 Small and medium-sized 121,031 21,369 142,400 1,759 Retail: Housing Loan 37,006 25,563 62,569 1,073 Others 37,884 21,016 58,900 806 Total domestic 996,250 84,035 1,080,285 16,688 Foreign: Total foreign 117,300 26,696 143,996 2,422 Total 1,113,550 110,731 1,224,281 19,110 September 30, 2021 Domestic: Corporate: Large companies 815,107 19,018 834,125 6,787 Small and medium-sized 123,862 16,906 140,768 867 Retail: Housing Loan 31,588 23,407 54,995 477 Others 40,762 22,639 63,401 406 Total domestic 1,011,319 81,970 1,093,289 8,537 Foreign: Total foreign 98,892 7,632 106,524 843 Total 1,110,211 89,602 1,199,813 9,380 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 six months ended September 30, 2020 and 2021: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in millions of yen) September 30, 2020 Domestic: Corporate: Large companies — — 264,952 Small and medium-sized — — 54,760 Retail: Housing Loan — — 14,690 Others — — 9,130 Banks and other financial institutions — — 1,600 Total domestic — — 345,132 Foreign: Total foreign — — 80,889 Total — — 426,021 September 30, 2021 Domestic: Corporate: Large companies 5,849 22,757 375,248 Small and medium-sized — — 60,856 Retail: Housing Loan — — 4,996 Others — — 10,288 Total domestic 5,849 22,757 451,388 Foreign: Total foreign — — 21,206 Total 5,849 22,757 472,594 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 six months ended September 30, 2020 and 2021 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment September 30, 2020 September 30, 2021 (in millions of yen) Domestic: Corporate: Large companies 2,084 1,148 Small and medium-sized 3,861 2,157 Retail: Housing Loan 505 579 Others 1,104 515 Total domestic 7,554 4,399 Foreign: Total foreign 43,786 14,125 Total 51,340 18,524
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, 2021 and September 30, 2021: 30-59 days past due 60-89 days past due 90 days or more past Total past due Current Total (in millions of yen) March 31, 2021 Domestic: Corporate: Large companies 1,275 4,607 27,387 33,269 42,349,445 42,382,714 Small and medium-sized 1,386 — 9,185 10,571 3,275,570 3,286,141 Retail: Housing Loan 9,776 7,102 21,257 38,135 7,975,654 8,013,789 Others 5,165 1,123 12,012 18,300 1,872,454 1,890,754 Sovereign — — — — 2,235,890 2,235,890 Banks and other financial institutions — — — — 759,671 759,671 Total domestic 17,602 12,832 69,841 100,275 58,468,684 58,568,959 Foreign: Total foreign — 7,477 30,795 38,272 29,973,636 30,011,908 Total 17,602 20,309 100,636 138,547 88,442,320 88,580,867 30-59 days past due 60-89 days past due 90 days or more past Total past due Current Total (in millions of yen) September 30, 2021 Domestic: Corporate: Large companies — 3,149 22,168 25,317 41,677,686 41,703,003 Small and medium-sized 1,794 336 9,490 11,620 3,200,811 3,212,431 Retail: Housing Loan 14,521 7,250 19,092 40,863 7,841,596 7,882,459 Others 5,034 1,056 12,272 18,362 1,774,448 1,792,810 Sovereign — — — — 1,828,814 1,828,814 Banks and other financial institutions — — — — 710,961 710,961 Total domestic 21,349 11,791 63,022 96,162 57,034,316 57,130,478 Foreign: Total foreign — — 23,004 23,004 30,032,288 30,055,292 Total 21,349 11,791 86,026 119,166 87,066,604 87,185,770 Note: The majority of total foreign consist of corporate.

Allowance for credit losses o_2

Allowance for credit losses on loans (Tables)	6 Months Ended
	Sep. 30, 2021
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 six months ended September 30, 2020 and 2021 are shown below: Corporate Retail Total (in millions of yen) Six months ended September 30, 2020 Balance at beginning of period 413,026 27,829 440,855 April 1, 2020 adoption of CECL 77,514 78,241 155,755 Adjusted Balance at beginning of period 490,540 106,070 596,610 Provision (credit) for credit losses on loans 64,133 (11,051 ) 53,082 Charge-offs (28,417 ) (3,446 ) (31,863 ) Recoveries 5,260 479 5,739 Net charge-offs (23,157 ) (2,967 ) (26,124 ) Others (Note) (997 ) (45 ) (1,042 ) Balance at end of period 530,519 92,007 622,526 Six months ended September 30, 2021 Balance at beginning of period 562,470 88,379 650,849 Provision (credit) for credit losses on loans 49,695 (1,490 ) 48,205 Charge-offs (38,473 ) (2,423 ) (40,896 ) Recoveries 5,827 664 6,491 Net charge-offs (32,646 ) (1,759 ) (34,405 ) Others (Note) 579 — 579 Balance at end of period 580,098 85,130 665,228 Note: Others includes primarily foreign exchange translation.

Other assets and liabilities (T

Other assets and liabilities (Tables)	6 Months Ended
	Sep. 30, 2021
Details of Other Assets and Liabilities	The following table sets forth the details of other assets and liabilities at March 31, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions 2,339,902 1,668,239 Other 393,410 414,363 Collateral pledged: Collateral pledged for derivative transactions 1,088,847 900,101 Margins provided for futures contracts 297,496 338,584 Other 939,557 888,466 Prepaid pension cost 999,962 851,035 Right-of-use 611,533 594,381 Security deposits 104,915 103,728 Loans held for sale 29,834 46,749 Other 651,572 681,447 Total 7,457,028 6,487,093 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions 2,576,887 2,450,159 Other 403,501 425,615 Guaranteed trust principal (Note) 814,509 807,635 Lease 636,541 615,846 Collateral accepted: Collateral accepted for derivative transactions 763,642 721,662 Margins accepted for futures contracts 555,760 913,262 Unearned income 120,521 113,450 Other 1,337,397 1,457,152 Total 7,208,758 7,504,781 Note: 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 15 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred and common stock (Tab

Preferred and common stock (Tables)	6 Months Ended
	Sep. 30, 2021
Schedule of Stock by Class	The composition of preferred stock at March 31, 2021 and September 30, 2021 is as follows: Class of stock March 31, 2021 September 30, 2021 Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 90,000,000 — 90,000,000 — Class XV preferred stock 90,000,000 — 90,000,000 — Class XVI preferred stock 150,000,000 — 150,000,000 —

Accumulated other comprehensi_2

Accumulated other comprehensive income (loss), net of tax (Tables)	6 Months Ended
	Sep. 30, 2021
Changes in Each Component of AOCI	Changes in each component of Accumulated other comprehensive income (loss), net of tax (“AOCI”) for the six months ended September 30, 2020 and 2021 are as follows: Six months ended September 30, 2020 2021 (in millions of yen) AOCI, balance at beginning of period (9,494 ) 318,114 Net unrealized gains (losses) on available-for-sale Balance at beginning of period (19,592 ) (8,173 ) Unrealized holding gains (losses) during period 644 6,034 Less: reclassification adjustments for losses (gains) included in net income 754 (525 ) Change during period 1,398 5,509 Balance at end of period (18,194 ) (2,664 ) Foreign currency translation adjustments: Balance at beginning of period (109,872 ) (86,873 ) Foreign currency translation adjustments during period (36,652 ) 52,231 Less: reclassification adjustments for losses (gains) included in net income (409 ) — Change during period (37,061 ) 52,231 Balance at end of period (146,933 ) (34,642 ) Pension liability adjustments: Balance at beginning of period 69,455 397,153 Unrealized gains (losses) during period 190,394 (5,107 ) Less: reclassification adjustments for losses (gains) included in net income 672 (9,187 ) Change during period 191,066 (14,294 ) Balance at end of period 260,521 382,859 Own credit risk adjustments: Balance at beginning of period 50,515 16,007 Unrealized gains (losses) during period (9,340 ) (6,218 ) Less: reclassification adjustments for losses (gains) included in net income (2,732 ) 443 Change during period (12,072 ) (5,775 ) Balance at end of period 38,443 10,232 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 143,331 37,671 AOCI, balance at end of period 133,837 355,785
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 six months ended Sept e Six months ended September 30, 2021 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 income: Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale 738 (213 ) 525 — 525 Investment gains (losses)-net Pension liability adjustments 13,074 (3,875 ) 9,199 (12 ) 9,187 Salaries and employee Own credit risk adjustments (714 ) 219 (495 ) 52 (443 ) Other noninterest income Total 13,098 (3,869 ) 9,229 40 9,269 Notes: (1) The financial statement line item in which the amou n (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 and Net income, respectively.

Regulatory matters (Tables)

Regulatory matters (Tables)	6 Months Ended
	Sep. 30, 2021
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, 2021 and September 30, 2021 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: March 31, 2021 September 30, 2021 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (1) 5,405 8.01 5,379 8.01 Actual 7,850 11.63 8,244 12.27 Tier 1 capital: Required (1) 6,418 9.51 6,386 9.51 Actual 9,702 14.37 10,098 15.03 Total risk-based capital: Required (1) 7,767 11.51 7,729 11.51 Actual 11,385 16.87 11,927 17.76 Leverage Ratio (2) Required 6,016 3.00 6,108 3.00 Actual 9,702 4.83 10,098 4.96 MHBK: Common Equity Tier 1 capital: Required 2,823 4.50 2,794 4.50 Actual 6,972 11.11 7,340 11.82 Tier 1 capital: Required 3,764 6.00 3,726 6.00 Actual 8,819 14.05 9,187 14.79 Total risk-based capital: Required 5,019 8.00 4,967 8.00 Actual 10,400 16.57 10,924 17.59 Leverage Ratio (2) Required 5,660 3.00 5,700 3.00 Actual 8,819 4.67 9,187 4.83 MHTB: Common Equity Tier 1 capital: Required 82 4.50 81 4.50 Actual 527 28.94 479 26.70 Tier 1 capital: Required 109 6.00 108 6.00 Actual 527 28.94 479 26.70 Total risk-based capital: Required 146 8.00 144 8.00 Actual 527 28.94 479 26.71 Leverage Ratio (2) Required 138 3.00 129 3.00 Actual 527 11.41 479 11.17 March 31, 2021 September 30, 2021 Amount Ratio Amount Ratio (in billions of yen, except percentages) Non-consolidated: MHBK: Common Equity Tier 1 cap i Required 2,648 4.50 2,619 4.50 Actual 6,561 11.14 6,790 11.66 Tier 1 capital: Required 3,531 6.00 3,492 6.00 Actual 8,406 14.28 8,635 14.83 Total risk-based capital: Required 4,708 8.00 4,656 8.00 Actual 9,987 16.96 10,355 17.79 Leverage Ratio (2) Required 5,343 3.00 5,373 3.00 Actual 8,406 4.72 8,635 4.82 MHTB: Common Equity Tier 1 capital: Required 82 4.50 80 4.50 Actual 519 28.63 465 26.03 Tier 1 capital: Required 109 6.00 107 6.00 Actual 519 28.63 465 26.03 Total risk-based capital: Required 145 8.00 143 8.00 Actual 519 28.64 465 26.04 Leverage Ratio (2) Required 135 3.00 125 3.00 Actual 519 11.51 465 11.15 Notes: (1) The required ratios disclosed above, at March 31, 2021 and September 30, 2021, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01%, and the additional loss absorbency requirements for global systemically important banks (“G-SIBs”) (“D-SIBs”) (2) The required and actual amounts disclosed above at March 31, 2021 and September 30, 2021 exclude amounts of deposits to the Bank of Japan.

Earnings per common share (Tabl

Earnings per common share (Tables)	6 Months Ended
	Sep. 30, 2021
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 six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Net income: Net income attributable to MHFG common shareholders 315,886 312,657 Effect of dilutive securities — — Net income attributable to common shareholders after assumed conversions 315,886 312,657 Six months ended September 30, 2020 2021 (thousands of shares) Shares: Weighted average common shares outstanding 2,537,272 2,536,902 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 93 119 Weighted average common shares after assumed conversions 2,537,365 2,537,021 Six months ended September 30, 2020 2021 (in yen) Earnings per common share: Basic net income per common share 124.50 123.24 Diluted net income per common share (Note) 124.49 123.24 Note: For the six months ended September 30, 2020, 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.

Income taxes (Tables)

Income taxes (Tables)	6 Months Ended
	Sep. 30, 2021
Components of Income Tax Expense	The following table presents the components of Income tax expense for the six months ended September 30, 2020 and 2021: Six months ended 2020 2021 (in millions of yen) Current tax expense 79,954 67,822 Deferred tax expense (benefit) 57,807 (28,200 ) Total income tax expense 137,761 39,622
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 six months ended September 30, 2020 and 2021. The detailed amounts recorded directly in Equity are as follows: Six months ended 2020 2021 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 579 926 Less: reclassification adjustments 306 (213 ) Total 885 713 Pension liability adjustments: Unrealized gains (losses) 83,994 (2,144 ) Less: reclassification adjustments 321 (3,875 ) Total 84,315 (6,019 ) Own credit risk adjustments: Unrealized gains (losses) (2,351 ) (2,638 ) Less: reclassification adjustments (1,259 ) 219 Total (3,610 ) (2,419 ) Total tax effect before allocation to noncontrolling interests 81,590 (7,725 )

Pension and other employee be_2

Pension and other employee benefit plans (Tables)	6 Months Ended
	Sep. 30, 2021
Components of Net Periodic Benefit Cost of Severance Indemnities and Pension Plans	The following table summarizes the components of net periodic benefit cost of the severance indemnities and pension plans of the MHFG Group for the six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 2021 (in millions of yen) Service cost-benefits earned during the period 22,695 16,365 Interest costs on projected benefit obligations 2,931 2,700 Expected return on plan assets (20,073 ) (18,478 ) Amortization of prior service cost (benefits) 205 (2,410 ) Amortization of net actuarial loss (gain) 836 (10,263 ) Special termination benefits 4,981 4,154 Net periodic benefit cost 11,575 (7,932 )

Derivative financial instrume_2

Derivative financial instruments (Tables)	6 Months Ended
	Sep. 30, 2021
Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding	The following table summarizes the notional and fair value amounts of derivative instruments outstan d Fair value Derivative receivables (2) Derivative payables (2) March 31, 2021 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,174,835 — 4,639 — 4,476 Foreign exchange contracts 182,809 — 3,328 — 3,246 Equity-related contracts 7,865 — 531 — 384 Credit-related contracts 10,431 — 94 — 113 Other contracts 413 — 33 — 33 Total 1,376,353 — 8,625 — 8,252 Fair value Derivative receivables (2) Derivative payables (2) September 30, 2021 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,061,161 — 3,404 — 3,245 Foreign exchange contracts 192,620 — 2,487 — 2,383 Equity-related contracts 9,782 — 495 — 328 Credit-related contracts 11,478 — 116 — 136 Other contracts 528 — 63 — 65 Total 1,275,569 — 6,565 — 6,157 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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 3,687 71 4,150 86 Non-investment 872 17 916 22 Total 4,559 88 5,066 108 Credit protection purchased 5,872 (107 ) 6,412 (128 ) 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, 2021 and September 30, 2021: Maximum payout/Notional amount March 31, 2021 September 30, 2021 (in billions of yen) One year or less 249 230 After one year through five years 4,184 4,662 After five years 126 174 Total 4,559 5,066 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
Not Designated as Hedging Instrument
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 six months ended September 30, 2020 and 2021: Gains (losses) recorded in income for six months ended September 30, 2020 2021 (in millions of yen) Interest rate contracts 32,791 20,602 Foreign exchange contracts 26,277 7,407 Equity-related contracts (31,999 ) 33,504 Credit-related contracts (Note) (29,219 ) (15,599 ) Other contracts 26,692 6,875 Total 24,542 52,789 Note: Amounts include the net gains (losses) of ¥(1,221) million and ¥(395) million on the credit derivatives economically managing the cr e
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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 780 587 Collateral provided to counterparties in the normal course of business 584 436 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 196 151
Net Investment Hedging | Designated as Hedging Instrument
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes gains and losses information related to net investment hedges for the six months ended September 30, 2020 and 2021: Gains (losses) recorded in other for six months ended September 30, 2020 2021 (in millions of yen) Financial instruments hedging foreign exchange risk 1,538 (1,241 ) Total 1,538 (1,241 ) Note: No amount related to the net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the six months ended September 30, 2021. Related to the net investment hedges, gains (losses) of ¥(1,312) million was reclassified from Accumulated other comprehensive income to earnings for the six months ended September 30, 2020.

Commitments and contingencies (

Commitments and contingencies (Tables)	6 Months Ended
	Sep. 30, 2021
Summary of Maximum Potential Amount of Future Payments under Guarantees	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. March 31, 2021 September 30, 2021 (in billions of yen) Performance guarantees 2,730 2,764 Guarantees on loans 348 448 Guarantees on securities 79 69 Other guarantees 2,390 2,558 Guarantees for the repayment of trust principal 28 25 Liabilities of trust accounts 480 466 Derivative financial instruments 23,933 26,445
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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Commitments to extend credit (Note) 93,999 87,549 Commercial letters of credit 797 1,028 Total 94,796 88,577 Note: Commitments to extend credit include commitments to invest in securities.
Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees
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, 2021 and September 30, 2021: March 31, 2021 September 30, 2021 (in billions of yen) Investment grade 4,427 4,583 Non-investment 1,120 1,256 Total 5,547 5,839 Note: Investment grade in the internal rating scale generally corresponds to BBB-

Variable interest entities an_2

Variable interest entities and securitizations (Tables)	6 Months Ended
	Sep. 30, 2021
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, 2021 and September 30, 2021: Consolidated VIEs Significant unconsolidated VIEs March 31, 2021 Consolidated assets Total assets Maximum exposure to (in billions of yen) Asset-backed commercial paper/loan programs 2,628 — — Asset-backed securitizations 921 127 48 Investments in securitization products 390 — — Investment funds 2,299 3,219 768 Trust arrangements and other 5,535 — — Total 11,773 3,346 816 Consolidated VIEs Significant unconsolidated VIEs September 30, 2021 Consolidated assets Total assets Maximum exposure to (in billions of yen) Asset-backed commercial paper/loan programs 2,537 — — Asset-backed securitizations 1,198 138 57 Investments in securitization products 394 — — Investment funds 2,146 3,052 716 Trust arrangements and other 5,525 — — Total 11,800 3,190 773
Unconsolidated VIEs
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, 2021 and September 30, 2021: Assets on balance sheets related to unconsolidated VIEs: March 31, 2021 September 30, 2021 (in billions of yen) Trading account assets 127 130 Investments 513 464 Loans 66 68 Total 706 662 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: March 31, 2021 September 30, 2021 (in billions of yen) Payables under securities lending transactions 53 55 Trading account liabilities 2 2 Total 55 57 Maximum exposure to loss (Note) 816 773 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)	6 Months Ended
	Sep. 30, 2021
Summary of Noninterest Income	Details of Noninterest income for the six months ended September 30, 2020 and 2021 are as follows: Six months ended September 30, 2020 2021 (in millions of yen) Fee and commission income: Securities-related business (1) 78,441 89,387 Deposits-related business (1) 7,408 7,569 Lending-related business (2)(4) 79,619 78,053 Remittance business (1) 54,785 54,576 Asset management business (1) 45,948 60,596 Trust-related business (1) 54,425 66,393 Agency business (1) 15,064 18,573 Guarantee-related business (3) 15,560 16,781 Fees for other customer services (1) 77,067 82,988 Total Fee and commission income 428,317 474,916 Foreign exchange gains (losses)—net (3) 22,785 21,708 Trading account gains (losses)—net (2) 257,591 83,255 Investment gains (losses)—net: Debt securities (3) 46 (317 ) Equity securities (3) 266,119 135,070 Equity in earnings (losses) of equity method investees-net (3) 5,788 16,541 Gains on disposal of premises and equipment (3) 6,849 1,988 Other noninterest income (2) (5) 23,715 29,234 Total 1,011,210 762,395 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 17 “Fair value” for further details.

Fair value (Tables)

Fair value (Tables)	6 Months Ended
	Sep. 30, 2021
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, 2021 and September 30, 2021, including those for which the MHFG Group has elected the fair value option, are summarized below: March 31, 2021 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,923 11 — 1,934 Japanese local government bonds — 120 — 120 U.S. Treasury bonds and federal agency securities 3,544 604 — 4,148 Other foreign government bonds 775 500 — 1,275 Agency mortgage-backed securities — 4,727 — 4,727 Residential mortgage-backed securities — — 9 9 Certificates of deposit and commercial paper — 1,204 — 1,204 Corporate bonds and other (2) 34 1,638 1,033 2,705 Equity securities 1,220 326 29 1,575 Trading securities measured at net asset value (3) 431 Derivative financial instruments: Interest rate contracts 63 4,564 12 4,639 Foreign exchange contracts — 3,304 24 3,328 Equity-related contracts 170 339 22 531 Credit-related contracts — 91 3 94 Other contracts 10 6 17 33 Available-for-sale Japanese government bonds 20,598 323 — 20,921 Japanese local government bonds — 463 — 463 U.S. Treasury bonds and federal agency securities 911 — — 911 Other foreign government bonds 535 972 — 1,507 Agency mortgage-backed securities — 521 — 521 Residential mortgage-backed securities — 48 23 71 Commercial mortgage-backed securities — — 716 716 Japanese corporate bonds and other debt securities — 1,539 365 1,904 Foreign corporate bonds and other debt securities — 707 132 839 Equity securities: Equity securities with readily determinable fair values 3,375 104 — 3,479 Equity securities measured at net asset value (3) 121 Other investments 2 — 53 55 Total assets measured at fair value on a recurring basis 33,160 22,111 2,438 58,261 Liabilities: Trading securities sold, not yet purchased 2,138 488 — 2,626 Derivative financial instruments: Interest rate contracts 64 4,408 4 4,476 Foreign exchange contracts — 3,245 1 3,246 Equity-related contracts 224 117 43 384 Credit-related contracts — 112 1 113 Other contracts 7 9 17 33 Long-term debt (4) — 1,990 713 2,703 Total liabilities measured at fair value on a recurring basis 2,433 10,369 779 13,581 September 30, 2021 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 2,612 9 — 2,621 Japanese local government bonds — 74 — 74 U.S. Treasury bonds and federal agency securities 4,900 770 — 5,670 Other foreign government bonds 760 527 — 1,287 Agency mortgage-backed securities — 4,715 — 4,715 Residential mortgage-backed securities — — 8 8 Certificates of deposit and commercial paper — 1,121 — 1,121 Corporate bonds and other (2) 58 1,780 826 2,664 Equity securities 1,961 227 30 2,218 Trading securities measured at net asset value (3) 374 Derivative financial instruments: Interest rate contracts 31 3,363 10 3,404 Foreign exchange contracts — 2,464 23 2,487 Equity-related contracts 189 283 23 495 Credit-related contracts — 113 3 116 Other contracts 26 4 33 63 Available-for-sale Japanese government bonds 18,807 196 — 19,003 Japanese local government bonds — 495 — 495 U.S. Treasury bonds and federal agency securities 1,074 — — 1,074 Other foreign government bonds 444 887 — 1,331 Agency mortgage-backed securities — 599 — 599 Residential mortgage-backed securities — 44 20 64 Commercial mortgage-backed securities — 1 766 767 Japanese corporate bonds and other debt securities — 1,637 347 1,984 Foreign corporate bonds and other debt securities — 764 117 881 Equity securities: Equity securities with readily determinable fair values 3,717 106 — 3,823 Equity securities measured at net asset value (3) 160 Other investments 3 — 53 56 Total assets measured at fair value on a recurring basis 34,582 20,179 2,259 57,554 Liabilities: Trading securities sold, not yet purchased 2,172 805 — 2,977 Derivative financial instruments: Interest rate contracts 30 3,210 5 3,245 Foreign exchange contracts — 2,382 1 2,383 Equity-related contracts 167 99 62 328 Credit-related contracts — 134 2 136 Other contracts 18 15 32 65 Long-term debt (4) — 2,111 752 2,863 Total liabilities measured at fair value on a recurring basis 2,387 8,756 854 11,997 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, 2021 and September 30, 2021 were ¥55 billion and ¥54 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 six months ended September 30, 2020 and 2021: Six months ended September 30, 2020 April 1, 2020 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments September 30, 2020 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 10 — (2) — — — — — — (1 ) 9 — Corporate bonds and other 1,115 18 (2) — — (1 ) 189 (113 ) — (123 ) 1,085 18 Equity securities 30 (2 ) (2) — — — 2 — — — 30 (1 ) Derivative financial instruments, net (1) Interest rate contracts (5 ) (3 ) (2) — — — — — — 5 (3 ) 1 Foreign exchange contracts 16 4 (2) — — — — — — (1 ) 19 5 Equity-related contracts (17 ) 4 (2) — — — — — — 2 (11 ) 3 Credit-related contracts (2 ) 3 (2) — 1 1 — — — (2 ) 1 1 Other contracts 1 — (2) — — — — — — — 1 — Available-for-sale Residential mortgage-backed securities 31 — (3) — (4) — — — — — (4 ) 27 — Commercial mortgage-backed securities 615 — (3) 1 (4) — — 78 (51 ) — (2 ) 641 — Japanese corporate bonds and other debt securities 157 (7 ) (3) 8 (4) — — 344 — — (11 ) 491 — Foreign corporate bonds and other debt securities 174 1 (3) 8 (4) — — 31 — — (36 ) 178 — Other investments 39 (1 ) (3) — — — 38 (1 ) — (19 ) 56 (1 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — — 20 — — 20 — Long-term debt 621 (37 ) (5) (8 ) (4) 19 (35 ) — — 108 (120 ) 638 (27 ) Six months ended September 30, 2021 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 September 30, 2021 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed 9 — (2) — — — — — — (1 ) 8 — Corporate bonds and other 1,033 4 (2) — — (1 ) 232 (144 ) — (298 ) 826 5 Equity securities 29 1 (2) — — — — — — — 30 1 Derivative financial instruments, net (1) Interest rate contracts 8 (5 ) (2) — — — — — — 2 5 (5 ) Foreign exchange contracts 23 (1 ) (2) — — — — — — — 22 (2 ) Equity-related contracts (21 ) (14 ) (2) — — — — — — (4 ) (39 ) (22 ) Credit-related contracts 2 (1 ) (2) — (1 ) — — — — 1 1 1 Other contracts — 1 (2) — — — — — — — 1 — Available-for-sale Residential mortgage-backed 23 — (3) — (4) — — — — — (3 ) 20 — Commercial mortgage-backed 716 — (3) — (4) — — 63 (6 ) — (7 ) 766 — Japanese corporate bonds and other 365 2 (3) — (4) — — 8 — — (28 ) 347 2 Foreign corporate bonds and other 132 — (3) (3 ) (4) — — 19 — — (31 ) 117 — Other investments 53 (1 ) (3) — — — 34 (1 ) — (32 ) 53 (2 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — (1 ) 1 — — — — Long-term debt 713 6 (5) (5 ) (4) 1 (1 ) — — 256 (216 ) 752 9 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 OCI 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 September 30, 2020 and 2021. The amounts of unrealized gains (losses) in OCI are related to Available-for-sale securities and Long-term debt, which were ¥7 billion and ¥(8) billion, respectively, at September 30, 2020, and ¥nil billion and billion, respectively, at September 30, 2021. Transfers
Quantitative Information about Significant Unobservable Inputs Related to Material Classes of Level 3 Assets and Liabilities	Quantitative information about Level 3 fair value measurements The following table presents information about significant unobservable inputs related to the MHFG Group’s material classes of Level 3 assets and liabilities at March 31, 2021 and September 30, 2021: March 31, 2021 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 32 Discounted cash flow Prepayment rate Default rate Recovery rate Discount margin 2% - 17% 0% - 1% 100% - 100% 28bps - 170bps 7% Commercial mortgage-backed securities 716 Discounted cash flow Discount margin 5bps - 210bps 22bps Corporate bonds and other debt securities 1,530 Discounted cash flow Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 10% - 1% - 24% 10% - 68% 45bps - 143bps 4bps - 507bps 18% 2% 66% 115bps 284bps Derivative financial instruments, net: Interest rate contracts 8 Internal valuation model (3) IR – IR correlation 35% - 100% 76% Foreign exchange contracts 23 Internal valuation model (3) FX – IR correlation FX – FX correlation 23% - 50% 43% - 30% 54% Equity-related contracts (21 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25% - 25% 0% - 100% 8% - 71% 25% 88% 41% Credit-related contracts 2 Internal valuation model (3) Default rate Credit correlation 0% - 40% - 100% 1% 66% Other contracts — Internal valuation model (3) Commodity volatility 0% - 33% Long-term debt 713 Internal valuation model (3) IR – IR correlation FX – IR correlation FX – FX correlation Equity – IR correlation Equity – FX correlation Equity correlation Equity volatility Default rate Credit correlation 49% - 100% 23% - 50% 43% - 65% 25% - -33% - 50% 0% - 100% 8% - 71% 0% - 17% - 100% 78% 36% 54% 25% 0% 88% 29% 1% 68% September 30, 2021 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 28 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 1% - 17% 0% - 1% 100% - 100% 28bps - 170bps 6% 0% 100% 50bps Commercial mortgage-backed securities 766 Discounted cash flow Price-based Discount margin 6bps - 726bps 23bps Corporate bonds and other debt securities 1,290 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 22% - 24% 0% - 30 10% - 68% 25bps - 143bps 4bps - 502bps 24% 2% 65% 109bps 387bps Derivative financial instruments, net: Interest rate contracts 5 Internal valuation model (3) IR – IR correlation 23% - 100% 75% Foreign exchange contracts 22 Internal valuation model (3) FX – IR correlation FX – FX correlation 24% - 51% 41% - 65% 31% 53% Equity-related contracts (39 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25% - 25% 7% - 100% 7% - 101% 25% 89% 45% Credit-related contracts 1 Internal valuation model (3) Default rate Credit correlation 0% - 5% 41% - 100% 1% 67% Other contracts 1 Internal valuation model (3) Commodity volatility 0% - 41% 33% Long-term debt 752 Internal valuation model (3) IR – IR correlation FX – IR correlation FX – FX correlation Equity – IR correlation Equity – FX correlation Equity correlation Equity volatility Default rate Credit correlation 23% - 100% 24% - 51% 41% - 65% 25% - 25% -18% - 7% - 100% 7% - 101% 0% - 6% 17% - 100% 75% 39% 53% 25% 0% 89% 31% 1% 67% 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) This input represents the counterparty default rate derived from the MHFG Group’s own internal credit analyses. (5) 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. 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.
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, 2021 and September 30, 2021: March 31, 2021 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 85 — 3 82 167 Loans held-for-sale 22 — 21 1 23 Equity securities (without readily determinable fair values) 3 — — 3 4 Premises and equipment-net — — — — 7 Other assets 24 — — 24 34 Total assets measured at fair value on a nonrecurring basis 134 — 24 110 235 September 30, 2021 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 57 — — 57 102 Loans held-for-sale 21 — 11 10 22 Equity securities (without readily determinable fair values) 24 — 16 8 10 Other investments 3 3 — — 5 Total assets measured at fair value on a nonrecurring basis 105 3 27 75 139 Note: The fair values may not be current as of the dates indicated, but rather as of the da t
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, 2021 and September 30, 2021, 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”): March 31, 2021 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 63,910 63,910 47,441 16,469 — Investments 887 904 490 414 — Loans, net of allowance (Note) 87,708 88,845 — — 88,845 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 53,278 53,278 — 53,278 — Interest-bearing deposits 118,860 118,849 — 118,849 — Due to trust accounts 381 381 — 381 — Other short-term borrowings 9,086 9,086 — 9,086 — Long-term debt 9,034 9,219 — 7,847 1,372 September 30, 2021 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 67,649 67,649 46,328 21,321 — Investments 1,396 1,404 488 916 — Loans, net of allowance (Note) 86,299 87,555 — — 87,555 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 54,803 54,803 — 54,803 — Interest-bearing deposits 119,347 119,334 — 119,334 — Due to trust accounts 409 409 — 409 — Other short-term borrowings 9,039 9,039 — 9,039 — Long-term debt 9,184 9,367 — 7,895 1,472 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)	6 Months Ended
	Sep. 30, 2021
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, 2021 and September 30, 2021. 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) March 31, 2021 Assets (1) Derivatives 8,625 — 8,625 (5) (6,323 ) (588 ) 1,714 Receivables under resale agreements 11,623 — 11,623 (6) (10,478 ) — 1,145 Receivables under securities borrowing transactions 2,694 — 2,694 (7) (2,621 ) — 73 Total 22,942 — 22,942 (19,422 ) (588 ) 2,932 Liabilities (1) Derivatives 8,252 — 8,252 (5) (6,033 ) (933 ) 1,286 Payables under repurchase agreements 18,607 — 18,607 (6) (17,979 ) — 628 Payables under securities lending transactions 1,208 — 1,208 (7) (953 ) — 255 Total 28,067 — 28,067 (24,965 ) (933 ) 2,169 September 30, 2021 Assets (1) Derivatives 6,565 — 6,565 (5) (4,611 ) (557 ) 1,397 Receivables under resale agreements 16,933 — 16,933 (6) (15,890 ) — 1,043 Receivables under securities borrowing transactions 2,408 — 2,408 (7) (2,355 ) — 53 Total 25,906 — 25,906 (22,856 ) (557 ) 2,493 Liabilities (1) Derivatives 6,157 — 6,157 (5) (4,348 ) (748 ) 1,061 Payables under repurchase agreements 22,278 — 22,278 (6) (21,471 ) — 807 Payables under securities lending transactions 1,441 — 1,441 (7) (1,221 ) — 220 Total 29,876 — 29,876 (27,040 ) (748 ) 2,088 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 ¥8,168 billion and ¥7,652 billion, respectively, at March 31, 2021, and ¥6,256 billion and ¥5,808 billion, respectively, at September 30, 2021. (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 ¥10,551 billion and ¥18,321 billion, respectively, at March 31, 2021, and ¥15,957 billion and ¥21,817 billion, respectively, at September 30, 2021. (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 ¥2,694 billion and ¥958 billion, respectively, at March 31, 2021, and ¥2,408 billion and ¥1,229 billion, respectively, at September 30, 2021.

Repurchase agreements and sec_2

Repurchase agreements and securities lending transactions accounted for as secured borrowings (Tables)	6 Months Ended
	Sep. 30, 2021
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, 2021 and September 30, 2021: Overnight and continuous Up to 30 days 31-90 days Greater than 90 days Total (in billions of yen) March 31, 2021 Repurchase agreements 9,459 3,586 4,315 1,247 18,607 Securities lending transactions 943 15 — 250 1,208 Total 10,402 3,601 4,315 1,497 19,815 September 30, 2021 Repurchase agreements 14,303 3,151 3,082 1,742 22,278 Securities lending transactions 1,093 136 12 200 1,441 Total 15,396 3,287 3,094 1,942 23,719
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, 2021 and September 30, 2021: Repurchase agreements Securities lending transactions (in billions of yen) March 31, 2021 Japanese government bonds and Japanese local government bonds 1,787 352 Foreign government bonds and foreign agency mortgage-backed securities 15,917 131 Commercial paper and corporate bonds 284 57 Equity securities 544 654 Other 75 14 Total 18,607 1,208 September 30, 2021 Japanese government bonds and Japanese local government bonds 2,767 234 Foreign government bonds and foreign agency mortgage-backed securities 18,339 153 Commercial paper and corporate bonds 264 52 Equity securities 838 989 Other 70 13 Total 22,278 1,441

Business segment information (T

Business segment information (Tables)	6 Months Ended
	Sep. 30, 2021
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 MHFG (Consolidated) Six months ended September 30, 2020 (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) 314.2 226.6 226.0 293.0 23.8 9.7 1,093.3 General and administrative expenses (3) 313.5 104.0 125.2 105.3 15.7 15.6 679.3 Equity in earnings (losses) of equity method investees—net 3.5 2.4 5.9 — 0.4 (0.7 ) 11.5 Amortization of goodwill and others 1.1 0.1 0.2 0.4 3.8 0.5 6.1 Net business profits (losses) (4) 3.1 124.9 106.5 187.3 4.7 (7.1 ) 419.4 Fixed assets (5) 516.2 195.7 162.8 95.6 — 751.0 1,721.3 MHFG (Consolidated) Six months ended September 30, 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) 345.9 230.1 250.0 253.7 29.0 21.9 1,130.6 General and administrative expenses (3) 311.3 99.3 126.2 107.5 16.2 20.4 680.9 Equity in earnings (losses) of equity method investees—net 5.5 2.3 7.4 — 0.8 0.5 16.5 Amortization of goodwill and others 1.1 — 0.2 0.4 3.6 0.5 5.8 Net business profits (losses) (4) 39.0 133.1 131.0 145.8 10.0 1.5 460.4 Fixed assets (5) 538.6 182.5 166.7 96.3 — 738.2 1,722.3 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 investees-net (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 • 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 six months ended September 30, 2020 and 2021 presented above to income before income tax expense shown on the consolidated statements of income and a reconciliation of “Fixed assets” at September 30, 2020 and 2021 to the total amount of Premises and equipment-net, right-of-use Six months ended September 30, 2020 2021 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 419.4 460.4 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated 4.1 19.2 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (84.8 ) (59.9 ) Gains on reversal of reserves for possible losses on loans, and others 3.6 10.2 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others (50.5 ) (6.9 ) Net extraordinary gains (losses) 65.8 47.3 Others (24.2 ) (23.7 ) Income before income tax expense under Japanese GAAP 333.4 446.6 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (12.9 ) (47.9 ) Investments 285.4 13.8 Loans (10.8 ) 2.2 Allowances for credit losses 35.8 5.0 Premises and equipment (37.1 ) (34.9 ) Land revaluation 2.7 1.6 Business combinations (4.3 ) 3.4 Pension liabilities (84.5 ) (63.9 ) Consolidation of variable interest entities 36.6 51.1 Foreign currency translation (0.2 ) 2.4 Others 3.7 3.8 Income before income tax expense under U.S. GAAP 547.8 383.2
Reconciliation of Assets from Segment to Consolidated	As of September 30, 2020 2021 (in billions of yen) Fixed assets 1,721.3 1,722.3 U.S. GAAP adjustments (Note) 818.4 763.6 Premises and equipment-net, right-of-use 2,539.7 2,485.9 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from right-of-use

Basis of presentation - Additio

Basis of presentation - Additional Information (Detail)	Oct. 01, 2020
Disclosure of Accounting Policies [Line Items]
Stockholders equity stock consolidation	1-for-10 share

Investments - Amortized Cost, G

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale Securities (Detail) - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	¥ 26,199,419	¥ 27,856,703
Gross unrealized gains, available-for-sale securities		32,181	37,721
Gross unrealized losses, available-for-sale securities		32,888	41,389
Fair value, available-for-sale securities		26,198,712	27,853,035
Amortized cost, held-to-maturity securities	[1],[2]	1,395,648	887,149
Gross unrealized gains, held-to-maturity securities		14,640	19,733
Gross unrealized losses, held-to-maturity securities		6,705	3,273
Total		1,403,583	903,609
Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	19,029,022	20,953,200
Gross unrealized gains, available-for-sale securities		498	1,945
Gross unrealized losses, available-for-sale securities		26,477	34,562
Fair value, available-for-sale securities		19,003,043	20,920,583
Amortized cost, held-to-maturity securities	[1],[2]	479,970	479,959
Gross unrealized gains, held-to-maturity securities		7,437	9,555
Total		487,407	489,514
Debt securities | Japanese local government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	494,716	463,673
Gross unrealized gains, available-for-sale securities		713	544
Gross unrealized losses, available-for-sale securities		486	658
Fair value, available-for-sale securities		494,943	463,559
Debt securities | U.S. Treasury bonds and federal agency securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	1,070,555	906,499
Gross unrealized gains, available-for-sale securities		3,269	4,440
Gross unrealized losses, available-for-sale securities		69	46
Fair value, available-for-sale securities		1,073,755	910,893
Debt securities | Other foreign government bonds
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	1,331,043	1,505,770
Gross unrealized gains, available-for-sale securities		783	1,975
Gross unrealized losses, available-for-sale securities		889	209
Fair value, available-for-sale securities		1,330,937	1,507,536
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2],[3]	591,778	512,720
Gross unrealized gains, available-for-sale securities	[3]	8,467	8,746
Gross unrealized losses, available-for-sale securities	[3],[4]	853	687
Fair value, available-for-sale securities	[3]	599,392	520,779
Amortized cost, held-to-maturity securities	[1],[2],[5]	915,678	407,190
Gross unrealized gains, held-to-maturity securities	[5]	7,203	10,178
Gross unrealized losses, held-to-maturity securities	[5]	6,705	3,273
Total	[5]	916,176	414,095
Debt securities | Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	63,273	70,111
Gross unrealized gains, available-for-sale securities		706	761
Gross unrealized losses, available-for-sale securities		137	188
Fair value, available-for-sale securities		63,842	70,684
Debt securities | Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	760,959	709,938
Gross unrealized gains, available-for-sale securities		6,182	6,196
Gross unrealized losses, available-for-sale securities		224	39
Fair value, available-for-sale securities		766,917	716,095
Debt securities | Japanese corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2]	1,977,235	1,897,117
Gross unrealized gains, available-for-sale securities		9,962	10,537
Gross unrealized losses, available-for-sale securities		2,774	3,574
Fair value, available-for-sale securities		1,984,423	1,904,080
Debt securities | Foreign corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, net available-for-sale securities	[1],[2],[6]	880,838	837,675
Gross unrealized gains, available-for-sale securities	[6]	1,601	2,577
Gross unrealized losses, available-for-sale securities	[6]	979	1,426
Fair value, available-for-sale securities	[6]	¥ 881,460	¥ 838,826
[1]	Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 and included in Accrued income.
[2]	Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale securities were ¥13,617 million at March 31, 2021, and ¥11,466 million at September 30, 2021.
[3]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥520,746 million and ¥33 million, respectively, at March 31, 2021, and ¥599,359 million and ¥33 million, respectively, at September 30, 2021. 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.
[4]	Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥107,077 million at March 31, 2021, and ¥143,070 million at September 30, 2021. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[5]	All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.
[6]	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 ¥275,661 million at March 31, 2021, and ¥287,612 million at September 30, 2021.

Investments - Amortized Cost,_2

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale Securities (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		¥ 26,198,712	¥ 27,853,035
Amortised cost net of allowance for credit loss available for sale securities	[1],[2]	26,199,419	27,856,703
Net of Allowance for Credit Loss [Member]
Schedule of Investments [Line Items]
Amortised cost net of allowance for credit loss available for sale securities		11,466	13,617
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	[3]	599,392	520,779
Amortised cost net of allowance for credit loss available for sale securities	[1],[2],[3]	591,778	512,720
Debt securities | Negotiable certificates of deposits, asset- backed securities and collateral loan obligations
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		287,612	275,661
Debt securities | Japanese agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		599,359	520,746
Debt securities | Foreign agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		33	33
Available-for sale and held-to-maturity securities | Accrued Income [Member]
Schedule of Investments [Line Items]
Accrued interest receivables		¥ 8,951	¥ 10,379
[1]	Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 and included in Accrued income.
[2]	Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale securities were ¥13,617 million at March 31, 2021, and ¥11,466 million at September 30, 2021.
[3]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥520,746 million and ¥33 million, respectively, at March 31, 2021, and ¥599,359 million and ¥33 million, respectively, at September 30, 2021. 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.

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		Sep. 30, 2021	Mar. 31, 2021
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		¥ 13,146,685
Due after one year through five years, amortized cost		9,394,108
Due after five years through ten years,amortized cost		2,175,631
Due after ten years, amortized cost		1,482,995
Total		26,199,419
Due in one year or less, amortized cost		0
Due after one year through five years, amortized cost		479,970
Due after five years through ten years, amortized cost		0
Due after ten years, amortized cost		915,678
Amortized cost, held-to-maturity securities	[1],[2]	1,395,648	¥ 887,149
Due in one year or less, fair value		13,147,473
Due after one year through five years, fair value		9,393,046
Due after five years through ten years, fair value		2,163,556
Due after ten years, fair value		1,494,637
Total		26,198,712
Due in one year or less, fair value		0
Due after one year through five years, fair value		487,407
Due after five years through ten years, fair value		0
Due after ten years, fair value		916,176
Total		1,403,583	903,609
Debt securities | Japanese government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		11,112,193
Due after one year through five years, amortized cost		6,466,555
Due after five years through ten years,amortized cost		1,182,864
Due after ten years, amortized cost		267,410
Total		19,029,022
Due in one year or less, amortized cost		0
Due after one year through five years, amortized cost		479,970
Due after five years through ten years, amortized cost		0
Due after ten years, amortized cost		0
Amortized cost, held-to-maturity securities	[1],[2]	479,970	479,959
Due in one year or less, fair value		11,111,775
Due after one year through five years, fair value		6,460,865
Due after five years through ten years, fair value		1,166,584
Due after ten years, fair value		263,819
Total		19,003,043
Due in one year or less, fair value		0
Due after one year through five years, fair value		487,407
Due after five years through ten years, fair value		0
Due after ten years, fair value		0
Total		487,407	489,514
Debt securities | Japanese local government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		41,016
Due after one year through five years, amortized cost		241,693
Due after five years through ten years,amortized cost		204,491
Due after ten years, amortized cost		7,516
Total		494,716
Due in one year or less, fair value		41,027
Due after one year through five years, fair value		241,790
Due after five years through ten years, fair value		204,570
Due after ten years, fair value		7,556
Total		494,943
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		422,693
Due after one year through five years, amortized cost		647,862
Due after five years through ten years,amortized cost		0
Due after ten years, amortized cost		0
Total		1,070,555
Due in one year or less, fair value		423,719
Due after one year through five years, fair value		650,036
Due after five years through ten years, fair value		0
Due after ten years, fair value		0
Total		1,073,755
Debt securities | Other foreign government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		917,929
Due after one year through five years, amortized cost		410,999
Due after five years through ten years,amortized cost		1,059
Due after ten years, amortized cost		1,056
Total		1,331,043
Due in one year or less, fair value		917,972
Due after one year through five years, fair value		410,850
Due after five years through ten years, fair value		1,059
Due after ten years, fair value		1,056
Total		1,330,937
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		0
Due after ten years, amortized cost		591,778
Total		591,778
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		915,678
Amortized cost, held-to-maturity securities	[1],[2],[3]	915,678	407,190
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		599,392
Total		599,392
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		916,176
Total	[3]	916,176	¥ 414,095
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		63,273
Total		63,273
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		63,842
Total		63,842
Debt securities | Commercial mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		34,244
Due after one year through five years, amortized cost		338,785
Due after five years through ten years,amortized cost		385,530
Due after ten years, amortized cost		2,400
Total		760,959
Due in one year or less, fair value		34,263
Due after one year through five years, fair value		340,915
Due after five years through ten years, fair value		389,302
Due after ten years, fair value		2,437
Total		766,917
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		103,494
Due after one year through five years, amortized cost		996,194
Due after five years through ten years,amortized cost		333,038
Due after ten years, amortized cost		544,509
Total		1,977,235
Due in one year or less, fair value		103,477
Due after one year through five years, fair value		996,501
Due after five years through ten years, fair value		332,963
Due after ten years, fair value		551,482
Total		1,984,423
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		515,116
Due after one year through five years, amortized cost		292,020
Due after five years through ten years,amortized cost		68,649
Due after ten years, amortized cost		5,053
Total		880,838
Due in one year or less, fair value		515,240
Due after one year through five years, fair value		292,089
Due after five years through ten years, fair value		69,078
Due after ten years, fair value		5,053
Total		¥ 881,460
[1]	Accrued interest receivables are excluded from amortized cost, of which the amount were ¥10,379 million at March 31, 2021, and ¥8,951 million at September 30, 2021 and included in Accrued income.
[2]	Amortized cost, net of the allowance for credit losses, of which the amounts related to available-for-sale securities were ¥13,617 million at March 31, 2021, and ¥11,466 million at September 30, 2021.
[3]	All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.

Investments - Additional Inform

Investments - Additional Information (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Apr. 01, 2021	Mar. 31, 2021
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 493,573			¥ 460,025
Japanese corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Credit losses on available-for-sale securities	11		¥ 14
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	3	¥ 8
Held-to-maturity Securities | Japanese government bonds
Gain (Loss) on Securities [Line Items]
Credit losses on available-for-sale securities	0	0
Held-to-maturity Securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Credit losses on available-for-sale securities	¥ 0	¥ 0
Orient Corporation
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	49.00%
Chiba Kogya Bank LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	16.89%
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	15.00%
Mizuho Leasing Company LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	23.49%
Matthew International Capital Management LLC [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	16.31%
Custody Bank of Japan Ltd [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	27.00%
Equity securities (marketable)
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 247,864			229,156
Equity method Investments, aggregated market values	¥ 449,650			¥ 424,267

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		Sep. 30, 2021	Mar. 31, 2021
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		¥ 14,841,867	¥ 11,342,861
Less than 12 months Gross unrealized losses, available-for-sale securities		6,882	5,059
12 months or more Fair value, available-for-sale securities		3,026,177	5,090,903
12 months or more Gross unrealized losses, available-for-sale securities		26,006	36,330
Total Fair value, available-for-sale securities		17,868,044	16,433,764
Total Gross unrealized losses, available-for-sale securities		32,888	41,389
Debt securities | Japanese government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		13,200,228	9,998,772
Less than 12 months Gross unrealized losses, available-for-sale securities		4,197	1,924
12 months or more Fair value, available-for-sale securities		1,977,981	4,058,718
12 months or more Gross unrealized losses, available-for-sale securities		22,280	32,638
Total Fair value, available-for-sale securities		15,178,209	14,057,490
Total Gross unrealized losses, available-for-sale securities		26,477	34,562
Debt securities | Japanese local government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		93,142	125,058
Less than 12 months Gross unrealized losses, available-for-sale securities		137	323
12 months or more Fair value, available-for-sale securities		147,795	130,384
12 months or more Gross unrealized losses, available-for-sale securities		349	335
Total Fair value, available-for-sale securities		240,937	255,442
Total Gross unrealized losses, available-for-sale securities		486	658
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		39,048	38,625
Less than 12 months Gross unrealized losses, available-for-sale securities		69	46
12 months or more Fair value, available-for-sale securities		0
12 months or more Gross unrealized losses, available-for-sale securities		0
Total Fair value, available-for-sale securities		39,048	38,625
Total Gross unrealized losses, available-for-sale securities		69	46
Debt securities | Other foreign government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		622,377	576,415
Less than 12 months Gross unrealized losses, available-for-sale securities		856	209
12 months or more Fair value, available-for-sale securities		66,431
12 months or more Gross unrealized losses, available-for-sale securities		33
Total Fair value, available-for-sale securities		688,808	576,415
Total Gross unrealized losses, available-for-sale securities		889	209
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities	[1]	81,466	70,088
Less than 12 months Gross unrealized losses, available-for-sale securities	[1]	253	120
12 months or more Fair value, available-for-sale securities	[1]	61,604	36,989
12 months or more Gross unrealized losses, available-for-sale securities	[1]	600	567
Total Fair value, available-for-sale securities	[1]	143,070	107,077
Total Gross unrealized losses, available-for-sale securities	[1],[2]	853	687
Debt securities | Residential mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		6,862	9,270
Less than 12 months Gross unrealized losses, available-for-sale securities		28	52
12 months or more Fair value, available-for-sale securities		12,074	11,435
12 months or more Gross unrealized losses, available-for-sale securities		109	136
Total Fair value, available-for-sale securities		18,936	20,705
Total Gross unrealized losses, available-for-sale securities		137	188
Debt securities | Commercial mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		42,905	12,530
Less than 12 months Gross unrealized losses, available-for-sale securities		184	6
12 months or more Fair value, available-for-sale securities		9,786	10,351
12 months or more Gross unrealized losses, available-for-sale securities		40	33
Total Fair value, available-for-sale securities		52,691	22,881
Total Gross unrealized losses, available-for-sale securities		224	39
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		488,973	278,698
Less than 12 months Gross unrealized losses, available-for-sale securities		830	953
12 months or more Fair value, available-for-sale securities		690,315	843,026
12 months or more Gross unrealized losses, available-for-sale securities		1,944	2,621
Total Fair value, available-for-sale securities		1,179,288	1,121,724
Total Gross unrealized losses, available-for-sale securities		2,774	3,574
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		266,866	233,405
Less than 12 months Gross unrealized losses, available-for-sale securities		328	1,426
12 months or more Fair value, available-for-sale securities		60,191
12 months or more Gross unrealized losses, available-for-sale securities		651
Total Fair value, available-for-sale securities		327,057	233,405
Total Gross unrealized losses, available-for-sale securities	[3]	¥ 979	¥ 1,426
[1]	Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥107,077 million at March 31, 2021, and ¥143,070 million at September 30, 2021. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[2]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥520,746 million and ¥33 million, respectively, at March 31, 2021, and ¥599,359 million and ¥33 million, respectively, at September 30, 2021. 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.
[3]	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 ¥275,661 million at March 31, 2021, and ¥287,612 million at September 30, 2021.

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		Sep. 30, 2021	Mar. 31, 2021
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 17,868,044	¥ 16,433,764
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities	[1]	143,070	107,077
Debt securities | Domestic Government Sponsored Enterprises Debt Securities [Member] | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 143,070	¥ 107,077
[1]	Agency mortgage-backed securities presented in this line consist of Japanese agency mortgage-backed securities, of which the fair values were ¥107,077 million at March 31, 2021, and ¥143,070 million at September 30, 2021. 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	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Debt Securities, Available-for-sale [Line Items]
Gross realized gains	¥ 4,687	¥ 5,101
Gross realized losses	(3,925)	(3,694)
Net realized gains (losses) on sales of available-for-sale securities	¥ 762	¥ 1,407

Investments - Summary of Detail

Investments - Summary of Details of Net Gains and Losses on Equity Securities (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Gain (Loss) on Securities [Line Items]
Net gains (losses) recognized during the period on equity securities	[1]	¥ 135,070	¥ 266,119
Less: Net gains (losses) recognized during the period on equity securities sold during the period		29,552	34,985
Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period		¥ 105,518	¥ 231,134
[1]	These amounts are revenues from contracts that do not meet the scope of ASC 606.

Investments - Summary of Equity

Investments - Summary of Equity Securities Without Readily Determinable Fair Values (Detail) - JPY (¥) ¥ in Millions	Sep. 30, 2021	Mar. 31, 2021
Equity Securities without Readily Determinable Fair Value [Line Items]
Carrying amounts at the end of the period	¥ 208,869	¥ 186,146
Downward adjustments and impairments	6,580	5,087
Upward adjustments	¥ 24,126	¥ 9,216

Investments - Summary of Downwa

Investments - Summary of Downward Adjustments and Impairments and Upward Adjustments (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Equity Securities without Readily Determinable Fair Value [Line Items]
Downward adjustments and impairments	¥ 1,704	¥ 1,411
Upward adjustments	¥ 14,950	¥ 34

Investments - Summary of Compos

Investments - Summary of Composition of Other Investments (Detail) - JPY (¥) ¥ in Millions	Sep. 30, 2021	Mar. 31, 2021
Schedule of Investments [Line Items]
Equity method investments	¥ 493,573	¥ 460,025
Investments held by consolidated investment companies	60,728	55,321
Total	¥ 554,301	¥ 515,346

Loans - Loans Outstanding by Do

Loans - Loans Outstanding by Domicile and Industry of Borrower (Detail) - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		¥ 87,351,406	¥ 88,747,895
Less: Unearned income and deferred loan fees—net		165,636	167,028
Total loans before allowance for credit losses on loans		87,185,770	88,580,867
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		57,205,364	58,648,266
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,569,793	11,010,644
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,664,028	10,492,162
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		6,002,667	6,406,710
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,432,264	5,357,287
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,912,609	3,885,807
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[1]	4,231,331	4,695,677
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		1,596,867	1,898,137
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	5,997,987	5,918,260
Domestic | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,039,138	8,193,398
Domestic | Other individual loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		758,680	790,184
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		30,146,042	30,099,629
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	10,561,219	10,448,778
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		192,055	177,385
Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	19,368,406	19,454,623
Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		¥ 24,362	¥ 18,843
[1]	Banks and other financial institutions of domestic includes mainly banks, securities companies, insurance companies and credit card companies.
[2]	Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs.
[3]	Banks and other financial institutions of foreign includes mainly banks and financial services companies.
[4]	Commercial and industrial of foreign includes ¥221,908 million and ¥221,144 million of lease receivables that are receivables arising from direct financing leasing at March 31, 2021 and September 30, 2021, respectively.

Loans - Loans Outstanding by _2

Loans - Loans Outstanding by Domicile and Industry of Borrower (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Sep. 30, 2021	Mar. 31, 2021
Commercial and Industrial Sector [Member] | Geographic Distribution, Foreign [Member]
Direct Financing Lease, Lease Receivable	¥ 221,144	¥ 221,908

Loans - Additional Information

Loans - Additional Information (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net losses on sales of loans	¥ 1,674	¥ 1,178
Loans held for sale	46,749		¥ 29,834
Accrued Income [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivables	73,807
Impaired Financing Receivables with No Related Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans partially charged off	¥ 14,887		¥ 20,197

Loans - Credit Quality Informat

Loans - Credit Quality Information of Loans Based on MHFG Group's Internal Rating System (Detail) - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Normal obligors | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		¥ 447,717	¥ 785,194
2019		614,629	588,599
2018		550,698	588,535
2017		556,355	600,179
2016		571,772	741,969
Prior to 2016		5,039,717	4,599,546
Revolving loan		0	0
Total		7,780,888	7,904,022
Normal obligors | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		130,034	431,277
2019		319,234	154,675
2018		131,507	127,379
2017		107,610	88,649
2016		73,837	85,042
Prior to 2016		353,742	317,237
Revolving loan		507,467	526,703
Total		1,623,431	1,730,962
Watch obligors | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		481	2,041
2019		1,894	1,075
2018		845	1,566
2017		1,783	1,343
2016		1,142	2,127
Prior to 2016		40,431	39,046
Revolving loan		0	0
Total		46,576	47,198
Watch obligors | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		18,393	50,212
2019		41,274	14,288
2018		13,092	10,450
2017		9,820	5,888
2016		5,015	3,713
Prior to 2016		8,469	5,796
Revolving loan		9,915	10,545
Total		105,978	100,892
Nonaccrual loans | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		10,775	20,706
2019		7,452	2,268
2018		1,175	1,399
2017		1,349	1,421
2016		1,100	1,640
Prior to 2016		33,144	35,135
Revolving loan		0	0
Total		54,995	62,569
Nonaccrual loans | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		28,342	32,594
2019		9,376	2,086
2018		1,800	1,145
2017		1,062	901
2016		899	837
Prior to 2016		8,949	8,780
Revolving loan		12,973	12,557
Total		63,401	58,900
Financing Receivables Not Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		21,045,296	32,546,989
2019		15,600,109	13,017,576
2018		11,641,372	11,493,988
2017		10,046,247	4,770,628
2016		4,133,948	4,060,946
Prior to 2016		11,763,462	9,508,600
Revolving loan		12,955,336	13,182,140
Total		87,185,770	88,580,867
Financing Receivables Not Impaired | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		10,290,193	18,340,767
2019		10,085,257	7,937,280
2018		7,287,737	8,546,670
2017		7,757,000	3,613,978
2016		3,207,297	3,392,467
Prior to 2016		10,370,717	8,293,428
Revolving loan		8,132,277	8,444,369
Total		57,130,478	58,568,959
Financing Receivables Not Impaired | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		10,755,103	14,206,222
2019		5,514,852	5,080,296
2018		4,353,635	2,947,318
2017		2,289,247	1,156,650
2016		926,651	668,479
Prior to 2016		1,392,745	1,215,172
Revolving loan		4,823,059	4,737,771
Total		30,055,292	30,011,908
Financing Receivables Not Impaired | Normal obligors | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		844,284	1,466,468
2019		266,527	80,260
2018		85,704	128,702
2017		125,215	71,943
2016		72,379	75,389
Prior to 2016		425,654	389,777
Revolving loan		1,100	12,615
Total		1,820,863	2,225,154
Financing Receivables Not Impaired | Normal obligors | Domestic | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[1]	48,602	51,874
2019	[1]	24,845	135,135
2018	[1]	132,967	241,418
2017	[1]	221,456	24,097
2016	[1]	0	84,244
Prior to 2016	[1]	144,044	60,281
Revolving loan	[1]	139,047	162,622
Total	[1]	710,961	759,671
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		8,189,714	14,351,596
2019		8,020,885	6,173,182
2018		5,614,210	6,884,219
2017		6,241,858	2,384,565
2016		2,078,317	2,105,541
Prior to 2016		3,590,252	2,256,613
Revolving loan		6,537,575	6,819,851
Total		40,272,811	40,975,567
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		308,157	633,438
2019		496,873	463,744
2018		431,411	397,656
2017		339,670	224,791
2016		203,267	205,687
Prior to 2016		563,176	502,707
Revolving loan		521,714	518,612
Total		2,864,268	2,946,635
Financing Receivables Not Impaired | Normal obligors | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		65,240	96,177
2019		44,751	78,727
2018		53,723	26,569
2017		24,142	157,256
2016		158,689	0
Prior to 2016		3,532	4,474
Revolving loan		61,176	69,320
Total		411,253	432,523
Financing Receivables Not Impaired | Normal obligors | Foreign | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[2]	636,823	1,030,080
2019	[2]	345,528	317,635
2018	[2]	197,395	275,695
2017	[2]	249,809	18,272
2016	[2]	16,127	1,497
Prior to 2016	[2]	1,506	3,105
Revolving loan	[2]	28,627	25,145
Total	[2]	1,475,815	1,671,429
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		9,887,658	12,813,813
2019		4,993,722	4,614,310
2018		4,023,459	2,558,432
2017		1,961,077	922,526
2016		730,828	655,823
Prior to 2016		1,347,278	1,143,658
Revolving loan		4,614,140	4,501,155
Total		27,558,162	27,209,717
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		1,130	2,100
2019		1,569	2,342
2018		1,978	1,468
2017		1,199	1,034
2016		522	1,074
Prior to 2016		3,510	1,401
Revolving loan		17	18
Total		9,925	9,437
Financing Receivables Not Impaired | Watch obligors | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		951	4,312
2019		5,118	3,594
2018		1,145	2,164
2017		576	635
2016		161	31
Prior to 2016		0	0
Revolving loan		0	0
Total		7,951	10,736
Financing Receivables Not Impaired | Watch obligors | Domestic | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[1]	0	0
2019	[1]	0	0
2018	[1]	0	0
2017	[1]	0	0
2016	[1]	0	0
Prior to 2016	[1]	0	0
Revolving loan	[1]	0	0
Total	[1]	0	0
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		81,285	151,406
2019		96,286	86,390
2018		84,448	86,199
2017		81,316	61,785
2016		47,014	40,907
Prior to 2016		64,902	35,681
Revolving loan		140,816	128,363
Total		596,067	590,731
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		33,846	62,300
2019		36,441	24,245
2018		31,820	30,007
2017		27,171	13,547
2016		13,205	13,536
Prior to 2016		34,406	24,430
Revolving loan		30,506	29,041
Total		207,395	197,106
Financing Receivables Not Impaired | Watch obligors | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		0	0
2019		0	0
2018		0	0
2017		0	0
2016		0	0
Prior to 2016		0	20,118
Revolving loan		0	0
Total		0	20,118
Financing Receivables Not Impaired | Watch obligors | Foreign | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[2]	0	6,341
2019	[2]	5,390	0
2018	[2]	152	78
2017	[2]	608	0
2016	[2]	0	4,774
Prior to 2016	[2]	0	0
Revolving loan	[2]	0	0
Total	[2]	6,150	11,193
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		149,058	196,054
2019		106,849	36,915
2018		40,203	72,529
2017		44,477	54,514
2016		19,720	894
Prior to 2016		16,717	25,009
Revolving loan		110,385	127,553
Total		487,409	513,468
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		0	0
2019		0	0
2018		40	0
2017		0	14
2016		0	0
Prior to 2016		14	13
Revolving loan		0	0
Total		54	27
Financing Receivables Not Impaired | Nonaccrual loans | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		0	0
2019		0	0
2018		0	0
2017		0	0
2016		0	0
Prior to 2016		0	0
Revolving loan		0	0
Total		0	0
Financing Receivables Not Impaired | Nonaccrual loans | Domestic | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[1]	0	0
2019	[1]	0	0
2018	[1]	0	0
2017	[1]	0	0
2016	[1]	0	0
Prior to 2016	[1]	0	0
Revolving loan	[1]	0	0
Total	[1]	0	0
Financing Receivables Not Impaired | Nonaccrual loans | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		84,652	219,111
2019		121,840	196,945
2018		198,406	38,490
2017		38,431	129,066
2016		136,798	28,650
Prior to 2016		54,315	9,547
Revolving loan		199,683	194,607
Total		834,125	816,416
Financing Receivables Not Impaired | Nonaccrual loans | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		62,960	78,238
2019		22,583	10,794
2018		8,509	7,341
2017		3,328	5,168
2016		2,391	3,154
Prior to 2016		9,516	8,852
Revolving loan		31,481	28,853
Total		140,768	142,400
Financing Receivables Not Impaired | Nonaccrual loans | Foreign | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		0	0
2019		0	710
2018		653	0
2017		0	0
2016		0	0
Prior to 2016		0	0
Revolving loan		0	0
Total		653	710
Financing Receivables Not Impaired | Nonaccrual loans | Foreign | Financial institutions borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	[2]	0	0
2019	[2]	0	0
2018	[2]	0	0
2017	[2]	0	0
2016	[2]	0	0
Prior to 2016	[2]	0	0
Revolving loan	[2]	0	0
Total	[2]	0	0
Financing Receivables Not Impaired | Nonaccrual loans | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		15,194	61,657
2019		17,043	29,657
2018		36,032	12,547
2017		7,935	3,034
2016		765	4,417
Prior to 2016		20,188	17,394
Revolving loan		8,714	14,580
Total		105,871	143,286
Financing Receivables Not Impaired | Nonaccrual loans | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020		0	0
2019		0	0
2018		0	0
2017		0	0
2016		0	0
Prior to 2016		0	0
Revolving loan		0	0
Total		¥ 0	¥ 0
[1]	Banks and other financial institutions of domestic includes mainly banks and securities companies.
[2]	Banks and other financial institutions of foreign includes mainly banks.

Loans - Impaired Loans Informat

Loans - Impaired Loans Information (Detail) - JPY (¥) ¥ in Millions	6 Months Ended	12 Months Ended
	Sep. 30, 2021	Mar. 31, 2021
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	¥ 1,110,211	¥ 1,113,550
Nonaccrual loans without an allowance	89,602	110,731
Total nonaccrual loans	1,199,813	1,224,281
Interest income recognized	9,380	19,110
Domestic
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	1,011,319	996,250
Nonaccrual loans without an allowance	81,970	84,035
Total nonaccrual loans	1,093,289	1,080,285
Interest income recognized	8,537	16,688
Domestic | Retail | Housing loan
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	31,588	37,006
Nonaccrual loans without an allowance	23,407	25,563
Total nonaccrual loans	54,995	62,569
Interest income recognized	477	1,073
Domestic | Retail | Other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	40,762	37,884
Nonaccrual loans without an allowance	22,639	21,016
Total nonaccrual loans	63,401	58,900
Interest income recognized	406	806
Domestic | Large companies | Corporate
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	815,107	800,329
Nonaccrual loans without an allowance	19,018	16,087
Total nonaccrual loans	834,125	816,416
Interest income recognized	6,787	13,050
Domestic | Small and medium sized companies | Corporate
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	123,862	121,031
Nonaccrual loans without an allowance	16,906	21,369
Total nonaccrual loans	140,768	142,400
Interest income recognized	867	1,759
Foreign
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans with an allowance	98,892	117,300
Nonaccrual loans without an allowance	7,632	26,696
Total nonaccrual loans	106,524	143,996
Interest income recognized	¥ 843	¥ 2,422

Loans - Troubled Debt Restructu

Loans - Troubled Debt Restructurings Entered Modified Periods by Type of Concession Granted (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	¥ 5,849	¥ 0
Loan forgiveness or debt to equity swaps charge-offs		22,757	0
Interest rate reduction and/or postponement of principal and/or interest		472,594	426,021
Domestic
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	5,849	0
Loan forgiveness or debt to equity swaps charge-offs		22,757	0
Interest rate reduction and/or postponement of principal and/or interest		451,388	345,132
Domestic | Housing loan | Retail
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	0
Loan forgiveness or debt to equity swaps charge-offs		0
Interest rate reduction and/or postponement of principal and/or interest		4,996	14,690
Domestic | Other | Retail
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	0
Loan forgiveness or debt to equity swaps charge-offs		0
Interest rate reduction and/or postponement of principal and/or interest		10,288	9,130
Domestic | Large companies | Corporate
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	5,849	0
Loan forgiveness or debt to equity swaps charge-offs		22,757	0
Interest rate reduction and/or postponement of principal and/or interest		375,248	264,952
Domestic | Small and medium sized companies | Corporate
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	0
Loan forgiveness or debt to equity swaps charge-offs		0
Interest rate reduction and/or postponement of principal and/or interest		60,856	54,760
Domestic | Banks and other financial institutions
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest			1,600
Foreign
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	0	0
Loan forgiveness or debt to equity swaps charge-offs		0	0
Interest rate reduction and/or postponement of principal and/or interest		¥ 21,206	¥ 80,889
[1]	Amounts represent the book values of loans immediately after the restructurings.

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 Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 18,524	¥ 51,340
Housing loan
Financing Receivable, Modifications [Line Items]
Recorded investment	579	505
Other
Financing Receivable, Modifications [Line Items]
Recorded investment	515	1,104
Domestic
Financing Receivable, Modifications [Line Items]
Recorded investment	4,399	7,554
Domestic | Corporate | Large companies
Financing Receivable, Modifications [Line Items]
Recorded investment	1,148	2,084
Domestic | Corporate | Small and medium sized companies
Financing Receivable, Modifications [Line Items]
Recorded investment	2,157	3,861
Foreign
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 14,125	¥ 43,786

Loans - Age Analysis of Past Du

Loans - Age Analysis of Past Due Loans (Detail) - JPY (¥) ¥ in Millions	6 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	¥ 18,524	¥ 51,340
Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	579	505
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	515	1,104
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	4,399	7,554
Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,148	2,084
Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	2,157	3,861
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	14,125	¥ 43,786
30-59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	21,349		¥ 17,602
30-59 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	21,349		17,602
30-59 Days Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
30-59 Days Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0		1,275
30-59 Days Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,794		1,386
30-59 Days Past Due | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	14,521		9,776
30-59 Days Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	5,034		5,165
30-59 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
30-59 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0		0
60-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	11,791		20,309
60-89 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	11,791		12,832
60-89 Days Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
60-89 Days Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	3,149		4,607
60-89 Days Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	336		0
60-89 Days Past Due | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	7,250		7,102
60-89 Days Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,056		1,123
60-89 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
60-89 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0		7,477
90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	86,026		100,636
90 Days or More Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	63,022		69,841
90 Days or More Past Due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
90 Days or More Past Due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	22,168		27,387
90 Days or More Past Due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	9,490		9,185
90 Days or More Past Due | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	19,092		21,257
90 Days or More Past Due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	12,272		12,012
90 Days or More Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
90 Days or More Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	23,004		30,795
Total past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	119,166		138,547
Total past due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	96,162		100,275
Total past due | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
Total past due | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	25,317		33,269
Total past due | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	11,620		10,571
Total past due | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	40,863		38,135
Total past due | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	18,362		18,300
Total past due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	0
Total past due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	23,004		38,272
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	87,066,604		88,442,320
Current | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	57,034,316		58,468,684
Current | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,828,814		2,235,890
Current | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	41,677,686		42,349,445
Current | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	3,200,811		3,275,570
Current | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	7,841,596		7,975,654
Current | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,774,448		1,872,454
Current | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	710,961		759,671
Current | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	30,032,288		29,973,636
Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	87,185,770		88,580,867
Total | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	57,130,478		58,568,959
Total | Domestic | Soverign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,828,814		2,235,890
Total | Domestic | Corporate | Large companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	41,703,003		42,382,714
Total | Domestic | Corporate | Small and medium sized companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	3,212,431		3,286,141
Total | Domestic | Retail | Housing loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	7,882,459		8,013,789
Total | Domestic | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	1,792,810		1,890,754
Total | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	710,961		759,671
Total | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	¥ 30,055,292		¥ 30,011,908

Allowance for Credit Losses o_3

Allowance for Credit Losses on Loans (Changes in Allowance for Credit Losses On Loan and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment) (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL		¥ 650,849	¥ 440,855
Provision (credit) for credit losses on loans		48,205	53,082
Charge-offs		(40,896)	(31,863)
Recoveries		6,491	5,739
Net charge-offs		(34,405)	(26,124)
Others	[1]	579	(1,042)
Balance at end of fiscal year		665,228	622,526
Cumulative effect of change in accounting principles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			596,610
Cumulative effect, period of adoption, adjusted balance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			155,755
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL		562,470	413,026
Provision (credit) for credit losses on loans		49,695	64,133
Charge-offs		(38,473)	(28,417)
Recoveries		5,827	5,260
Net charge-offs		(32,646)	(23,157)
Others	[1]	579	(997)
Balance at end of fiscal year		580,098	530,519
Corporate | Cumulative effect of change in accounting principles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			490,540
Corporate | Cumulative effect, period of adoption, adjusted balance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			77,514
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL		88,379	27,829
Provision (credit) for credit losses on loans		(1,490)	(11,051)
Charge-offs		(2,423)	(3,446)
Recoveries		664	479
Net charge-offs		(1,759)	(2,967)
Others	[1]	0	(45)
Balance at end of fiscal year		¥ 85,130	92,007
Retail | Cumulative effect of change in accounting principles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			106,070
Retail | Cumulative effect, period of adoption, adjusted balance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Adoption of CECL			¥ 78,241
[1]	Others includes primarily foreign exchange translation.

Other Assets and Liabilities (D

Other Assets and Liabilities (Details of Other Assets and Liabilities) (Detail) - JPY (¥) ¥ in Millions		Sep. 30, 2021	Mar. 31, 2021
Other assets:
Receivables from brokers, dealers and customers for securities transactions		¥ 1,668,239	¥ 2,339,902
Other		414,363	393,410
Collateral pledged for derivative transactions		900,101	1,088,847
Margins provided for futures contracts		338,584	297,496
Other		888,466	939,557
Prepaid pension cost		851,035	999,962
Right-of-use assets		594,381	611,533
Security deposits		103,728	104,915
Loans held for sale		46,749	29,834
Other		681,447	651,572
Total		6,487,093	7,457,028
Other liabilities:
Payables to brokers, dealers and customers for securities transactions		2,450,159	2,576,887
Other		425,615	403,501
Guaranteed trust principal	[1]	807,635	814,509
Lease liabilities		¥ 615,846	636,541
Operating Lease, Liability, Statement of Financial Position [Extensible List]		Lease liabilities
Collateral accepted for derivative transactions		¥ 721,662	763,642
Margins accepted for futures contracts		913,262	555,760
Unearned income		113,450	120,521
Other		1,457,152	1,337,397
Total		¥ 7,504,781	¥ 7,208,758
[1]	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 15 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Preferred and Common Stock (Com

Preferred and Common Stock (Composition of Preferred Stock) (Detail) - shares	Sep. 30, 2021	Mar. 31, 2021
Class Fourteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	90,000,000	90,000,000
Number of shares Issued	0	0
Class Fifteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	90,000,000	90,000,000
Number of shares Issued	0	0
Class Sixteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	150,000,000	150,000,000
Number of shares Issued	0	0

Preferred and Common Stock - Ad

Preferred and Common Stock - Additional Information (Detail) - shares	Sep. 30, 2021	Mar. 31, 2021
Class of Stock [Line Items]
Common Stock, Shares, Issued	2,539,249,894	2,539,249,894

Accumulated other comprehensi_3

Accumulated other comprehensive income (loss), net of tax (Changes in Each Component of AOCI) (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		¥ 9,688,157
Less: reclassification adjustments for losses (gains) included in net income		(9,229)
Change during period		38,196	¥ 142,550
Balance at end of fiscal year		10,042,141	9,140,053
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	[1]	318,114	(9,494)
Change during period	[1]	37,671	143,331
Balance at end of fiscal year	[1]	355,785	133,837
Net unrealized gains (losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(8,173)	(19,592)
Unrealized gains (losses) during period		6,034	644
Less: reclassification adjustments for losses (gains) included in net income		(525)	754
Change during period		5,509	1,398
Balance at end of fiscal year		(2,664)	(18,194)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(86,873)	(109,872)
Foreign currency translation adjustments during period		52,231	(36,652)
Less: reclassification adjustments for losses (gains) included in net income		0	(409)
Change during period		52,231	(37,061)
Balance at end of fiscal year		(34,642)	(146,933)
Pension liability adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		397,153	69,455
Unrealized gains (losses) during period		(5,107)	190,394
Less: reclassification adjustments for losses (gains) included in net income		(9,187)	672
Change during period		(14,294)	191,066
Balance at end of fiscal year		382,859	260,521
Accumulated Own Credit Risk Adjustment Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		16,007	50,515
Unrealized gains (losses) during period		(6,218)	(9,340)
Less: reclassification adjustments for losses (gains) included in net income		443	(2,732)
Change during period		(5,775)	(12,072)
Balance at end of fiscal year		¥ 10,232	¥ 38,443
[1]	The amounts that have been reclassified out of Accumulated other comprehensive income (loss), net of tax into net income are presented in Note 8 “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	6 Months Ended
	Sep. 30, 2021JPY (¥)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	¥ 13,098	[1]
Tax effect	(3,869)	[2]
Net of tax before allocation to noncontrolling interests	9,229
Net of tax attributable to noncontrolling interests	40	[2]
Net of tax attributable to MHFG shareholders	9,269
Accumulated Net Unrealized Investment Gain (Loss) | Gain (Loss) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	738	[1]
Tax effect	(213)	[2]
Net of tax before allocation to noncontrolling interests	525
Net of tax attributable to noncontrolling interests	0	[2]
Net of tax attributable to MHFG shareholders	525
Accumulated Defined Benefit Plans Adjustment | Salaries and employee benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	13,074	[1]
Tax effect	(3,875)	[2]
Net of tax before allocation to noncontrolling interests	9,199
Net of tax attributable to noncontrolling interests	(12)	[2]
Net of tax attributable to MHFG shareholders	9,187
Accumulated Own Credit Risk Adjustment | Other Noninterest Income (Expenses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	(714)	[1]
Tax effect	219	[2]
Net of tax before allocation to noncontrolling interests	(495)
Net of tax attributable to noncontrolling interests	52	[2]
Net of tax attributable to MHFG shareholders	¥ (443)
[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 and Net income, respectively.

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 Billions		Sep. 30, 2021	Mar. 31, 2021
Mizuho Financial Group Inc | Consolidated
Common Equity Tier 1 capital:
Required	[1]	¥ 5,379	¥ 5,405
Actual		8,244	7,850
Required	[1]	6,386	6,418
Actual		¥ 10,098	¥ 9,702
Required	[1]	9.51%	9.51%
Actual		15.03%	14.37%
Required	[1]	¥ 7,729	¥ 7,767
Actual		¥ 11,927	¥ 11,385
Required	[1]	11.51%	11.51%
Actual		17.76%	16.87%
Required	[2]	¥ 6,108	¥ 6,016
Actual	[2]	¥ 10,098	¥ 9,702
Common Equity Tier 1 capital:
Required	[1]	8.01%	8.01%
Actual		12.27%	11.63%
Leverage Ratio:
Required	[2]	3.00%	3.00%
Actual	[2]	4.96%	4.83%
Mizuho Bank Limited | Consolidated
Common Equity Tier 1 capital:
Required		¥ 2,794	¥ 2,823
Actual		7,340	6,972
Required		3,726	3,764
Actual		¥ 9,187	¥ 8,819
Required		6.00%	6.00%
Actual		14.79%	14.05%
Required		¥ 4,967	¥ 5,019
Actual		¥ 10,924	¥ 10,400
Required		8.00%	8.00%
Actual		17.59%	16.57%
Required	[2]	¥ 5,700	¥ 5,660
Actual	[2]	¥ 9,187	¥ 8,819
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		11.82%	11.11%
Leverage Ratio:
Required	[2]	3.00%	3.00%
Actual	[2]	4.83%	4.67%
Mizuho Bank Limited | Non-consolidated
Common Equity Tier 1 capital:
Required		¥ 2,619	¥ 2,648
Actual		6,790	6,561
Required		3,492	3,531
Actual		¥ 8,635	¥ 8,406
Required		6.00%	6.00%
Actual		14.83%	14.28%
Required		¥ 4,656	¥ 4,708
Actual		¥ 10,355	¥ 9,987
Required		8.00%	8.00%
Actual		17.79%	16.96%
Required	[2]	¥ 5,373	¥ 5,343
Actual	[2]	¥ 8,635	¥ 8,406
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		11.66%	11.14%
Leverage Ratio:
Required	[2]	3.00%	3.00%
Actual	[2]	4.82%	4.72%
Mizuho Trust & Banking Company Limited | Consolidated
Common Equity Tier 1 capital:
Required		¥ 81	¥ 82
Actual		479	527
Required		108	109
Actual		¥ 479	¥ 527
Required		6.00%	6.00%
Actual		26.70%	28.94%
Required		¥ 144	¥ 146
Actual		¥ 479	¥ 527
Required		8.00%	8.00%
Actual		26.71%	28.94%
Required	[2]	¥ 129	¥ 138
Actual	[2]	¥ 479	¥ 527
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		26.70%	28.94%
Leverage Ratio:
Required	[2]	3.00%	3.00%
Actual	[2]	11.17%	11.41%
Mizuho Trust & Banking Company Limited | Non-consolidated
Common Equity Tier 1 capital:
Required		¥ 80	¥ 82
Actual		465	519
Required		107	109
Actual		¥ 465	¥ 519
Required		6.00%	6.00%
Actual		26.03%	28.63%
Required		¥ 143	¥ 145
Actual		¥ 465	¥ 519
Required		8.00%	8.00%
Actual		26.04%	28.64%
Required	[2]	¥ 125	¥ 135
Actual	[2]	¥ 465	¥ 519
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		26.03%	28.63%
Leverage Ratio:
Required	[2]	3.00%	3.00%
Actual	[2]	11.15%	11.51%
[1]	The required ratios disclosed above, at March 31, 2021 and September 30, 2021, include the capital conservation buffer of 2.5%, the countercyclical capital buffer of 0.01%, and the additional loss absorbency requirements for global systemically important banks (“G-SIBs”) and domestic systemically important banks (“D-SIBs”) of 1.0%, which 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 September 30, 2021 exclude amounts of deposits to the Bank of Japan.

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)	6 Months Ended	12 Months Ended
	Sep. 30, 2021	Mar. 31, 2021
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer	2.50%	2.50%
March 2020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Countercyclical capital buffer	0.01%	0.01%
March 2021
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	1.00%

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		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Net income:
Net income attributable to MHFG common shareholders		¥ 312,657	¥ 315,886
Effect of dilutive securities
Net income attributable to common shareholders after assumed conversions		¥ 312,657	¥ 315,886
Shares:
Weighted average common shares outstanding		2,536,902	2,537,272
Effect of dilutive securities:
Stock options and the common shares of MHFG under the stock compensation programs	[1]	119	93
Weighted average common shares after assumed conversions		2,537,021	2,537,365
Earnings per common share:
Basic net income per common share		¥ 123.24	¥ 124.50
Diluted net income per common share	[1]	¥ 123.24	¥ 124.49
[1]	For the six months ended September 30, 2020, 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.

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Reconciliation of Provision of Income Taxes [Line Items]
Current tax expense	¥ 67,822	¥ 79,954
Deferred tax expense (benefit)	(28,200)	57,807
Total income tax expense	¥ 39,622	¥ 137,761

Income Taxes (Detailed Amounts

Income Taxes (Detailed Amounts of Tax Effects of Items Recorded Directly in Equity) (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Net unrealized gains (losses) on available-for-sale securities:
Unrealized gains (losses)	¥ 926	¥ 579
Less: reclassification adjustments	(213)	306
Total	713	885
Pension liability adjustments:
Unrealized gains (losses)	(2,144)	83,994
Less: reclassification adjustments	(3,875)	321
Total	(6,019)	84,315
Own credit risk adjustments:
Unrealized gains (losses)	(2,638)	(2,351)
Less: reclassification adjustments	219	(1,259)
Total	(2,419)	(3,610)
Total tax effect before allocation to noncontrolling interests	¥ (7,725)	¥ 81,590

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Income Taxes [Line Items]
Statutory tax rate	30.62%	30.62%
Effective tax rate	10.34%	25.15%
Net operating loss carryforwards	¥ 788,000
Unrecognized Tax Benefits	¥ 4,492

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	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the period	¥ 16,365	¥ 22,695
Interest costs on projected benefit obligations	2,700	2,931
Expected return on plan assets	(18,478)	(20,073)
Amortization of prior service cost (benefits)	(2,410)	205
Amortization of net actuarial loss (gain)	(10,263)	836
Special termination benefits	4,154	4,981
Net periodic benefit cost	¥ (7,932)	¥ 11,575

Pension and Other Employee Be_4

Pension and Other Employee Benefit Plans - Additional Information (Detail) ¥ in Millions	6 Months Ended
	Sep. 30, 2020JPY (¥)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, prior service costs recognised	¥ 73,998
Defined contribution plans effective date	Oct. 1, 2020

Derivative Financial Instrume_3

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding) (Detail) - JPY (¥) ¥ in Billions		Sep. 30, 2021	Mar. 31, 2021
Derivatives, Fair Value [Line Items]
Notional amount	[1]	¥ 1,275,569	¥ 1,376,353
Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	1,061,161	1,174,835
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	192,620	182,809
Equity-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	9,782	7,865
Credit-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	11,478	10,431
Other contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	528	413
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	6,565	8,625
Fair value of derivative payables	[2]	6,157	8,252
Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	3,404	4,639
Fair value of derivative payables	[2]	3,245	4,476
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	2,487	3,328
Fair value of derivative payables	[2]	2,383	3,246
Not Designated as Hedging Instrument | Equity-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	495	531
Fair value of derivative payables	[2]	328	384
Not Designated as Hedging Instrument | Credit-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	116	94
Fair value of derivative payables	[2]	136	113
Not Designated as Hedging Instrument | Other contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	63	33
Fair value of derivative payables	[2]	¥ 65	¥ 33
[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 Billions	Sep. 30, 2021	Mar. 31, 2021
Derivative [Line Items]
Cash collateral provided and not offset against derivative positions and included in Other assets	¥ 900	¥ 1,108
Cash collateral accepted and not offset against derivative positions and included in Other liabilities	¥ 722	¥ 764

Derivative Financial Instrume_5

Derivative Financial Instruments (Summary of Gains and Losses Information Related to Net Investment Hedges) (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in OCI	¥ (1,241)	¥ 1,538
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in OCI	¥ (1,241)	¥ 1,538

Derivative Financial Instrume_6

Derivative Financial Instruments (Summary of Gains and Losses Information Related to Net Investment Hedges) (Parenthetical) (Detail) ¥ in Millions	Sep. 30, 2020JPY (¥)
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income reclassified to earnings	¥ 1,312

Derivative Financial Instrume_7

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 52,789	¥ 24,542
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		20,602	32,791
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		7,407	26,277
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		33,504	(31,999)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	(15,599)	(29,219)
Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 6,875	¥ 26,692
[1]	Amounts include the net gains (losses) of ¥(1,221) million and ¥(395) million on the credit derivatives economically managing the credit risk of loans during the six months ended September 30, 2020 and 2021, respectively.

Derivative Financial Instrume_8

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 52,789	¥ 24,542
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	(15,599)	(29,219)
Credit-related contracts | Loans related to credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (395)	¥ (1,221)
[1]	Amounts include the net gains (losses) of ¥(1,221) million and ¥(395) million on the credit derivatives economically managing the credit risk of loans during the six months ended September 30, 2020 and 2021, respectively.

Derivative Financial Instrume_9

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Credit Derivatives) (Detail) - JPY (¥) ¥ in Billions	Sep. 30, 2021	Mar. 31, 2021
Credit protection written
Credit Derivatives [Line Items]
Notional amount	¥ 5,066	¥ 4,559
Fair value	108	88
Credit protection written | Investment grade
Credit Derivatives [Line Items]
Notional amount	4,150	3,687
Fair value	86	71
Credit protection written | Non-investment grade
Credit Derivatives [Line Items]
Notional amount	916	872
Fair value	22	17
Credit protection purchased
Credit Derivatives [Line Items]
Notional amount	6,412	5,872
Fair value	¥ (128)	¥ (107)

Derivative Financial Instrum_10

Derivative Financial Instruments (Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period) (Detail) - JPY (¥) ¥ in Billions	Sep. 30, 2021	Mar. 31, 2021
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 5,066	¥ 4,559
One year or less
Credit Derivatives [Line Items]
Maximum payout/Notional amount	230	249
After one year through five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	4,662	4,184
After five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 174	¥ 126

Derivative Financial Instrum_11

Derivative Financial Instruments (Quantitative Information about Derivative Instruments with Credit-risk-related Contingent Features) (Detail) - JPY (¥) ¥ in Billions	Sep. 30, 2021	Mar. 31, 2021
Credit Derivatives [Line Items]
Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions	¥ 587	¥ 780
Collateral provided to counterparties in the normal course of business	436	584
Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered	¥ 151	¥ 196

Commitments and Contingencies_2

Commitments and Contingencies (Summary of Maximum Potential Amount of Future Payments under Guarantees) (Detail) - JPY (¥) ¥ in Billions	Sep. 30, 2021	Mar. 31, 2021
Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 2,764	¥ 2,730
Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	448	348
Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	69	79
Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	2,558	2,390
Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	25	28
Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	466	480
Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 26,445	¥ 23,933

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		Sep. 30, 2021	Mar. 31, 2021
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 5,839	¥ 5,547
Investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	[1]	4,583	4,427
Non-investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 1,256	¥ 1,120
[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		Sep. 30, 2021	Mar. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 88,577	¥ 94,796
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]	87,549	93,999
Commercial letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 1,028	¥ 797
[1]	Commitments to extend credit include commitments to invest in securities.

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	Sep. 30, 2021	Mar. 31, 2021
Variable Interest Entity [Line Items]
Total assets of MHFG	¥ 222,769,638	¥ 221,651,474
Significant unconsolidated VIEs- Maximum exposure to loss	773,000	816,000
Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	11,799,744	11,773,405
Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	3,190,000	3,346,000
Asset-backed commercial paper/loan programs | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	2,537,000	2,628,000
Asset-backed securitizations
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	57,000	48,000
Asset-backed securitizations | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	1,198,000	921,000
Asset-backed securitizations | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	138,000	127,000
Investments in securitization products | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	394,000	390,000
Investment funds
Variable Interest Entity [Line Items]
Significant unconsolidated VIEs- Maximum exposure to loss	716,000	768,000
Investment funds | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	2,146,000	2,299,000
Investment funds | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	3,052,000	3,219,000
Trust arrangements and other | Consolidated VIEs
Variable Interest Entity [Line Items]
Total assets of MHFG	¥ 5,525,000	¥ 5,535,000

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		Sep. 30, 2021	Mar. 31, 2021
Assets on consolidated balance sheets
Trading account assets		¥ 27,317,435	¥ 26,753,109
Loans		86,520,542	87,930,018
Total assets		222,769,638	221,651,474
Liabilities on MHFG's consolidated balance sheets and maximum exposure to loss related to unconsolidated VIEs
Payables under securities lending transactions		1,441,179	1,208,031
Trading account liabilities		9,134,179	10,877,538
Total		212,727,497	211,963,317
Maximum exposure to loss		773,000	816,000
Unconsolidated VIEs
Assets on consolidated balance sheets
Total assets		3,190,000	3,346,000
Mizuho Financial Group Inc | Unconsolidated VIEs
Assets on consolidated balance sheets
Trading account assets		130,000	127,000
Investments		464,000	513,000
Loans		68,000	66,000
Total assets		662,000	706,000
Liabilities on MHFG's consolidated balance sheets and maximum exposure to loss related to unconsolidated VIEs
Payables under securities lending transactions		55,000	53,000
Trading account liabilities		2,000	2,000
Total		57,000	55,000
Maximum exposure to loss	[1]	¥ 773,000	¥ 816,000
[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	Sep. 30, 2021	Mar. 31, 2021
Consolidated MHFG's balance sheets
Long-term debt	¥ 12,021,499	¥ 11,706,471
Noncontrolling interests	693,366	582,919
Consolidated VIEs
Consolidated MHFG's balance sheets
Noncontrolling interests	564,000	464,000
Debt Instrument [Member]
Consolidated MHFG's balance sheets
Long-term debt	336,000	332,000
Assets associated with securitization transactions
Consolidated MHFG's balance sheets
Transferred assets continue to be carried on the consolidated balance sheets	153,000	176,000
Assets associated with loan participation transactions
Consolidated MHFG's balance sheets
Transferred assets continue to be carried on the consolidated balance sheets	¥ 179,000	¥ 181,000

Summary of Noninterest Income (

Summary of Noninterest Income (Detail) - JPY (¥) ¥ in Millions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 474,916	¥ 428,317
Foreign exchange gains (losses)—net	[1]	21,708	22,785
Trading account gains (losses)—net		83,255	257,591
Investment gains (losses)—net:
Debt securities	[1]	(317)	46
Equity securities	[1]	135,070	266,119
Equity in earnings (losses) of equity method investees—net	[1]	16,541	5,788
Gains on disposal of premises and equipment	[1]	1,988	6,849
Other noninterest income	[2],[3]	29,234	23,715
Total noninterest income		762,395	1,011,210
Securities related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	89,387	78,441
Deposits related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	7,569	7,408
Lending related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[2],[5]	78,053	79,619
Correspondent clearing
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	54,576	54,785
Investment advisory, management and administrative service
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	60,596	45,948
Fiduciary and trust
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	66,393	54,425
Agency business
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	18,573	15,064
Guarantee related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[1]	16,781	15,560
Financial service, other
Disaggregation of Revenue [Line Items]
Fee and commission income	[4]	82,988	77,067
Financial service
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 474,916	¥ 428,317
[1]	These amounts are revenues from contracts that do not meet the scope of 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 include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 17 “Fair value” for further details.
[4]	These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers” (“ASC 606”).
[5]	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		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Other Revenues [Line Items]
Trust fees		¥ 28,000	¥ 25,000
Fees related to trust business		38,000	29,000
Trading account gains (losses)—net		83,255	257,591
Other noninterest income	[1],[2]	29,234	23,715
Revenue from contracts with customers ("ASC 606")
Other Revenues [Line Items]
Trading account gains (losses)—net		42,000	45,000
Other noninterest income		¥ 7,000	¥ 7,000
[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 17 “Fair value” for further details.

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - JPY (¥) ¥ in Billions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	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	¥ 209		¥ 186
Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Into Level3		¥ 1
Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Out Of Level3	1	1
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	11		¥ 14
Net unrealized gains (losses) resulting from changes in fair values of the notes	¥ (30)	17
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 out of Level 3	¥ 1	35
Fair value of liabilities transferred into Level 3	1	19
Trading securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of assets transferred out of Level 3	¥ 1	¥ 1

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		Sep. 30, 2021	Mar. 31, 2021
Assets:
Available-for-sale securities		¥ 26,198,712	¥ 27,853,035
Liabilities:
Long-term debt		2,863,348	2,703,021
Fair Value, Measurements, Recurring
Assets:
Equity securities with readily determinable fair values		3,823,000	3,479,000
Equity securities measured at net asset value	[1]	160,000	121,000
Other investments		56,000	55,000
Total assets measured at fair value		57,554,000	58,261,000
Liabilities:
Trading securities sold, not yet purchased		2,977,000	2,626,000
Long-term debt		2,863,000	2,703,000	[2]
Total liabilities measured at fair value		11,997,000	13,581,000
Fair Value, Measurements, Recurring | Trading Account Asset
Assets:
Securities measured at net asset value	[1],[3]	374,000	431,000
Fair Value, Measurements, Recurring | Interest rate contracts
Assets:
Assets, derivatives		3,404,000	4,639,000
Liabilities:
Liabilities, derivatives		3,245,000	4,476,000
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets:
Assets, derivatives		2,487,000	3,328,000
Liabilities:
Liabilities, derivatives		2,383,000	3,246,000
Fair Value, Measurements, Recurring | Equity-related contracts
Assets:
Assets, derivatives		495,000	531,000
Liabilities:
Liabilities, derivatives		328,000	384,000
Fair Value, Measurements, Recurring | Credit-related contracts
Assets:
Assets, derivatives		116,000	94,000
Liabilities:
Liabilities, derivatives		136,000	113,000
Fair Value, Measurements, Recurring | Other contracts
Assets:
Assets, derivatives		63,000	33,000
Liabilities:
Liabilities, derivatives		65,000	33,000
Fair Value, Measurements, Recurring | Japanese government bonds
Assets:
Assets, trading securities	[3]	2,621,000	1,934,000
Available-for-sale securities		19,003,000	20,921,000
Fair Value, Measurements, Recurring | Japanese local government bonds
Assets:
Assets, trading securities	[3]	74,000	120,000
Available-for-sale securities		495,000	463,000
Fair Value, Measurements, Recurring | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	5,670,000	4,148,000
Available-for-sale securities		1,074,000	911,000
Fair Value, Measurements, Recurring | Other foreign government bonds
Assets:
Assets, trading securities	[3]	1,287,000	1,275,000
Available-for-sale securities		1,331,000	1,507,000
Fair Value, Measurements, Recurring | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	4,715,000	4,727,000
Available-for-sale securities		599,000	521,000
Fair Value, Measurements, Recurring | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	8,000	9,000
Available-for-sale securities		64,000	71,000
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		767,000	716,000
Fair Value, Measurements, Recurring | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	1,121,000	1,204,000
Fair Value, Measurements, Recurring | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	2,664,000	2,705,000	[4]
Fair Value, Measurements, Recurring | Equity securities
Assets:
Assets, trading securities	[3]	2,218,000	1,575,000
Fair Value, Measurements, Recurring | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,984,000	1,904,000
Fair Value, Measurements, Recurring | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		881,000	839,000
Fair Value, Measurements, Recurring | Level 1
Assets:
Equity securities with readily determinable fair values		3,717,000	3,375,000
Other investments		3,000	2,000
Total assets measured at fair value		34,582,000	33,160,000
Liabilities:
Trading securities sold, not yet purchased		2,172,000	2,138,000
Long-term debt		0
Total liabilities measured at fair value		2,387,000	2,433,000
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Assets:
Assets, derivatives		31,000	63,000
Liabilities:
Liabilities, derivatives		30,000	64,000
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Assets:
Assets, derivatives		0	0
Liabilities:
Liabilities, derivatives		0	0
Fair Value, Measurements, Recurring | Level 1 | Equity-related contracts
Assets:
Assets, derivatives		189,000	170,000
Liabilities:
Liabilities, derivatives		167,000	224,000
Fair Value, Measurements, Recurring | Level 1 | Credit-related contracts
Assets:
Assets, derivatives		0
Liabilities:
Liabilities, derivatives		0
Fair Value, Measurements, Recurring | Level 1 | Other contracts
Assets:
Assets, derivatives		26,000	10,000
Liabilities:
Liabilities, derivatives		18,000	7,000
Fair Value, Measurements, Recurring | Level 1 | Japanese government bonds
Assets:
Assets, trading securities	[3]	2,612,000	1,923,000
Available-for-sale securities		18,807,000	20,598,000
Fair Value, Measurements, Recurring | Level 1 | Japanese local government bonds
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	4,900,000	3,544,000
Available-for-sale securities		1,074,000	911,000
Fair Value, Measurements, Recurring | Level 1 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	760,000	775,000
Available-for-sale securities		444,000	535,000
Fair Value, Measurements, Recurring | Level 1 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 1 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 1 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 1 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	0
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	58,000	34,000	[4]
Fair Value, Measurements, Recurring | Level 1 | Equity securities
Assets:
Assets, trading securities	[3]	1,961,000	1,220,000
Fair Value, Measurements, Recurring | Level 1 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 1 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 2
Assets:
Equity securities with readily determinable fair values		106,000	104,000
Other investments		0
Total assets measured at fair value		20,179,000	22,111,000
Liabilities:
Trading securities sold, not yet purchased		805,000	488,000
Long-term debt		2,111,000	1,990,000	[2]
Total liabilities measured at fair value		8,756,000	10,369,000
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Assets:
Assets, derivatives		3,363,000	4,564,000
Liabilities:
Liabilities, derivatives		3,210,000	4,408,000
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets:
Assets, derivatives		2,464,000	3,304,000
Liabilities:
Liabilities, derivatives		2,382,000	3,245,000
Fair Value, Measurements, Recurring | Level 2 | Equity-related contracts
Assets:
Assets, derivatives		283,000	339,000
Liabilities:
Liabilities, derivatives		99,000	117,000
Fair Value, Measurements, Recurring | Level 2 | Credit-related contracts
Assets:
Assets, derivatives		113,000	91,000
Liabilities:
Liabilities, derivatives		134,000	112,000
Fair Value, Measurements, Recurring | Level 2 | Other contracts
Assets:
Assets, derivatives		4,000	6,000
Liabilities:
Liabilities, derivatives		15,000	9,000
Fair Value, Measurements, Recurring | Level 2 | Japanese government bonds
Assets:
Assets, trading securities	[3]	9,000	11,000
Available-for-sale securities		196,000	323,000
Fair Value, Measurements, Recurring | Level 2 | Japanese local government bonds
Assets:
Assets, trading securities	[3]	74,000	120,000
Available-for-sale securities		495,000	463,000
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	770,000	604,000
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 2 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	527,000	500,000
Available-for-sale securities		887,000	972,000
Fair Value, Measurements, Recurring | Level 2 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	4,715,000	4,727,000
Available-for-sale securities		599,000	521,000
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		44,000	48,000
Fair Value, Measurements, Recurring | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		1,000
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	1,121,000	1,204,000
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	1,780,000	1,638,000	[4]
Fair Value, Measurements, Recurring | Level 2 | Equity securities
Assets:
Assets, trading securities	[3]	227,000	326,000
Fair Value, Measurements, Recurring | Level 2 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,637,000	1,539,000
Fair Value, Measurements, Recurring | Level 2 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		764,000	707,000
Fair Value, Measurements, Recurring | Level 3
Assets:
Equity securities with readily determinable fair values		0
Other investments		53,000	53,000
Total assets measured at fair value		2,259,000	2,438,000
Liabilities:
Trading securities sold, not yet purchased		0
Long-term debt		752,000	713,000	[2]
Total liabilities measured at fair value		854,000	779,000
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Assets:
Assets, derivatives		10,000	12,000
Liabilities:
Liabilities, derivatives		5,000	4,000
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets:
Assets, derivatives		23,000	24,000
Liabilities:
Liabilities, derivatives		1,000	1,000
Fair Value, Measurements, Recurring | Level 3 | Equity-related contracts
Assets:
Assets, derivatives		23,000	22,000
Liabilities:
Liabilities, derivatives		62,000	43,000
Fair Value, Measurements, Recurring | Level 3 | Credit-related contracts
Assets:
Assets, derivatives		3,000	3,000
Liabilities:
Liabilities, derivatives		2,000	1,000
Fair Value, Measurements, Recurring | Level 3 | Other contracts
Assets:
Assets, derivatives		33,000	17,000
Liabilities:
Liabilities, derivatives		32,000	17,000
Fair Value, Measurements, Recurring | Level 3 | Japanese government bonds
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 3 | Japanese local government bonds
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 3 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 3 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	0
Available-for-sale securities		0
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	8,000	9,000
Available-for-sale securities		20,000	23,000
Fair Value, Measurements, Recurring | Level 3 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		766,000	716,000
Fair Value, Measurements, Recurring | Level 3 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	0
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	826,000	1,033,000	[4]
Fair Value, Measurements, Recurring | Level 3 | Equity securities
Assets:
Assets, trading securities	[3]	30,000	29,000
Fair Value, Measurements, Recurring | Level 3 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		347,000	365,000
Fair Value, Measurements, Recurring | Level 3 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		¥ 117,000	¥ 132,000
[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, 2021 and September 30, 2021 were ¥55 billion and ¥54 billion, respectively.
[2]	Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception.
[3]	Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option.
[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	Sep. 30, 2021	Mar. 31, 2021
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unfunded commitments	¥ 54	¥ 55

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	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Trading securities sold, not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	¥ 0
Gains (losses) in Earnings	0
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	(1)
Sales	1	¥ 20
Issuances	0
Settlements	0
Ending Balance	0	20
Change in unrealized gain (losses) still held	0
Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	713	621
Gains (losses) in Earnings	6	(37)
Gains (losses) in OCI	(5)	(8)
Transfers into Level 3	1	19
Transfers out of level 3	(1)	(35)
Purchases	0
Sales	0
Issuances	256	108
Settlements	(216)	(120)
Ending Balance	752	638
Change in unrealized gain (losses) still held	9	(27)
Trading securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers out of level 3	(1)	(1)
Trading securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	9	10
Gains (losses) in Earnings	0
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	(1)	(1)
Ending Balance	8	9
Change in unrealized gain (losses) still held	0
Trading securities | Corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,033	1,115
Gains (losses) in Earnings	4	18
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	(1)	(1)
Purchases	232	189
Sales	(144)	(113)
Issuances	0
Settlements	(298)	(123)
Ending Balance	826	1,085
Change in unrealized gain (losses) still held	5	18
Trading securities | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	29	30
Gains (losses) in Earnings	1	(2)
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0	2
Sales	0
Issuances	0
Settlements	0
Ending Balance	30	30
Change in unrealized gain (losses) still held	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	8	(5)
Gains (losses) in Earnings	(5)	(3)
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	2	5
Ending Balance	5	(3)
Change in unrealized gain (losses) still held	(5)	1
Derivative financial instruments assets | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	23	16
Gains (losses) in Earnings	(1)	4
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	0	(1)
Ending Balance	22	19
Change in unrealized gain (losses) still held	(2)	5
Derivative financial instruments assets | Equity-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	(21)	(17)
Gains (losses) in Earnings	(14)	4
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	(4)	2
Ending Balance	(39)	(11)
Change in unrealized gain (losses) still held	(22)	3
Derivative financial instruments assets | Credit-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	2	(2)
Gains (losses) in Earnings	(1)	3
Gains (losses) in OCI	0
Transfers into Level 3	(1)	1
Transfers out of level 3	0	1
Purchases	0
Sales	0
Issuances	0
Settlements	1	(2)
Ending Balance	1	1
Change in unrealized gain (losses) still held	1	1
Derivative financial instruments assets | Other contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	1
Gains (losses) in Earnings	1
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	0
Ending Balance	1	1
Change in unrealized gain (losses) still held	0
Available-for-sale securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	23	31
Gains (losses) in Earnings	0
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	0
Sales	0
Issuances	0
Settlements	(3)	(4)
Ending Balance	20	27
Change in unrealized gain (losses) still held	0
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	615
Gains (losses) in Earnings	0
Gains (losses) in OCI	0	1
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	63	78
Sales	(6)	(51)
Issuances	0
Settlements	(7)	(2)
Ending Balance	766	641
Change in unrealized gain (losses) still held	0
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	365	157
Gains (losses) in Earnings	2	(7)
Gains (losses) in OCI	0	8
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	8	344
Sales	0
Issuances	0
Settlements	(28)	(11)
Ending Balance	347	491
Change in unrealized gain (losses) still held	2
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	132	174
Gains (losses) in Earnings	0	1
Gains (losses) in OCI	(3)	8
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	19	31
Sales	0
Issuances	0
Settlements	(31)	(36)
Ending Balance	117	178
Change in unrealized gain (losses) still held	0
Available-for-sale securities | Other investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	53	39
Gains (losses) in Earnings	(1)	(1)
Gains (losses) in OCI	0
Transfers into Level 3	0
Transfers out of level 3	0
Purchases	34	38
Sales	(1)	(1)
Issuances	0
Settlements	(32)	(19)
Ending Balance	53	56
Change in unrealized gain (losses) still held	¥ (2)	¥ (1)

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	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Unrealized gains (losses) in OCI related to Available-for-sale securities	¥ 0	¥ 7
Unrealized gains (losses) in OCI related to Long-term debt	¥ (5)	¥ (8)

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		Sep. 30, 2021JPY (¥)		Mar. 31, 2021JPY (¥)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		¥ 2,863,348		¥ 2,703,021
Available For Sale And Trading Securities | Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		28,000		32,000
Available For Sale And Trading Securities | Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		766,000		716,000
Available For Sale And Trading Securities | Corporate bonds and other debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		1,290,000		1,530,000
Derivative Financial Instruments | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		5,000
Derivatives financial instruments				8,000
Derivative Financial Instruments | Foreign exchange contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		22,000		23,000
Derivative Financial Instruments | Equity-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		(39,000)		(21,000)
Derivative Financial Instruments | Credit-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		1,000		2,000
Derivative Financial Instruments | Other contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		1,000		0
Long-term debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		¥ 752,000		¥ 713,000
Minimum | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		0		0
Minimum | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				0
Minimum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		1		2
Minimum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		22	[1]	10
Minimum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0
Minimum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0	[1]	1
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		0		0
Minimum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		0		0
Minimum | Measurement Input Recovery Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				100
Minimum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100
Minimum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		10	[1]	10
Minimum | Measurement Input, Discount Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				28
Minimum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		28
Minimum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		25	[1]	45
Minimum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		6		5
Minimum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		4	[2]	4
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		23		35
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		23		49
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		24		23
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		24		23
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		41		43
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		41		43
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		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		25		25
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		18		(33)
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		7		8
Minimum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		7		8
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		41		40
Minimum | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		17		17
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		7		0
Minimum | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		7		0
Maximum | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		41		63
Maximum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		17		17
Maximum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		24		18
Maximum | Measurement Input, Default Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				1
Maximum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		1
Maximum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		30	[1]	24
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		5		5
Maximum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		6		5
Maximum | Measurement Input Recovery Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				100
Maximum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100
Maximum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		68	[1]	68
Maximum | Measurement Input, Discount Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				170
Maximum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		170
Maximum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		143	[1]	143
Maximum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		726		210
Maximum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		502	[2]	507
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		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		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		51		50
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		51		50
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		65		65
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		65		65
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		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		25		25
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		93		50
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		101		71
Maximum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt		101		71
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		100		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		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		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		100		100
Weighted Average | Other contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments		33		33
Weighted Average | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				7
Weighted Average | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		6
Weighted Average | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		24		18
Weighted Average | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				0
Weighted Average | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0
Weighted Average | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		2		2
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		1		1
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		1		1
Weighted Average | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				100
Weighted Average | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100
Weighted Average | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		65		66
Weighted Average | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities				51
Weighted Average | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[3]	50
Weighted Average | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		109	[1]	115
Weighted Average | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		23	[3]	22
Weighted Average | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		387	[2],[3]	284
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		75		76
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		75		78
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		31		30
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		39		36
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		53		54
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		53		54
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		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		25		25
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		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		45		41
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		31		29
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		67		66
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		67		68
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		89		88
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		89		88
[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]	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	Sep. 30, 2021	Mar. 31, 2021
Assets:
Equity securities (without readily determinable fair values)	¥ 208,869	¥ 186,146
Fair Value, Measurements, Nonrecurring
Assets:
Loans	57,000	85,000
Loans held-for-sale	21,000	22,000
Equity securities (without readily determinable fair values)	24,000	3,000
Other investments	3,000
Other assets		24,000
Total assets measured at fair value	105,000	134,000
Fair Value, Measurements, Nonrecurring | Aggregate cost
Assets:
Loans	102,000	167,000
Loans held-for-sale	22,000	23,000
Equity securities (without readily determinable fair values)	10,000	4,000
Other investments	5,000
Premises and equipment-net		7,000
Other assets		34,000
Total assets measured at fair value	139,000	235,000
Fair Value, Measurements, Nonrecurring | Level 1
Assets:
Loans	0
Loans held-for-sale	0
Equity securities (without readily determinable fair values)	0
Other investments	3,000
Total assets measured at fair value	3,000
Fair Value, Measurements, Nonrecurring | Level 2
Assets:
Loans	0	3,000
Loans held-for-sale	11,000	21,000
Equity securities (without readily determinable fair values)	16,000
Other investments	0
Total assets measured at fair value	27,000	24,000
Fair Value, Measurements, Nonrecurring | Level 3
Assets:
Loans	57,000	82,000
Loans held-for-sale	10,000	1,000
Equity securities (without readily determinable fair values)	8,000	3,000
Other investments	0
Other assets		24,000
Total assets measured at fair value	¥ 75,000	¥ 110,000

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		Sep. 30, 2021	Mar. 31, 2021
Financial liabilities:
Long-term debt		¥ 2,863,348	¥ 2,703,021
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		67,649,000	63,910,000
Investments		1,396,000	887,000
Loans, net of allowance	[1]	86,299,000	87,708,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		54,803,000	53,278,000
Interest-bearing deposits		119,347,000	118,860,000
Due to trust accounts		409,000	381,000
Other short-term borrowings		9,039,000	9,086,000
Long-term debt		9,184,000	9,034,000
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		67,649,000	63,910,000
Investments		1,404,000	904,000
Loans, net of allowance	[1]	87,555,000	88,845,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		54,803,000	53,278,000
Interest-bearing deposits		119,334,000	118,849,000
Due to trust accounts		409,000	381,000
Other short-term borrowings		9,039,000	9,086,000
Long-term debt		9,367,000	9,219,000
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		46,328,000	47,441,000
Investments		488,000	490,000
Loans, net of allowance	[1]	0
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		0
Interest-bearing deposits		0
Due to trust accounts		0
Other short-term borrowings		0
Long-term debt		0
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		21,321,000	16,469,000
Investments		916,000	414,000
Loans, net of allowance	[1]	0
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		54,803,000	53,278,000
Interest-bearing deposits		119,334,000	118,849,000
Due to trust accounts		409,000	381,000
Other short-term borrowings		9,039,000	9,086,000
Long-term debt		7,895,000	7,847,000
Estimated fair value | Level 3
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		0
Investments		0
Loans, net of allowance	[1]	87,555,000	88,845,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		0
Interest-bearing deposits		0
Due to trust accounts		0
Other short-term borrowings		0
Long-term debt		¥ 1,472,000	¥ 1,372,000
[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		Sep. 30, 2021	Mar. 31, 2021
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets, Gross amounts recognized	[1]	¥ 6,565	¥ 8,625
Derivative assets, Gross amounts offset on the balance sheet	[1]	0	0
Derivative assets, Net amounts presented on the balance sheet	[1],[2],[3]	6,565	8,625
Derivative assets, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(4,611)	(6,323)
Derivative assets, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	(557)	(588)
Derivative assets, Net amounts	[1]	1,397	1,714
Receivables under resale agreements, Gross amounts recognized	[1]	16,933	11,623
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]	16,933	11,623
Receivables under resale agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(15,890)	(10,478)
Receivables under resale agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Receivables under resale agreements, Net amounts	[1]	1,043	1,145
Receivables under securities borrowing transactions, Gross amounts recognized	[1]	2,408	2,694
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]	2,408	2,694
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(2,355)	(2,621)
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]	53	73
Financial assets, Gross amounts recognized, Total	[1]	25,906	22,942
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]	25,906	22,942
Financial assets, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[4],[5]	(22,856)	(19,422)
Financial assets, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[4]	(557)	(588)
Financial assets, Net amounts, Total	[1]	2,493	2,932
Derivative liabilities, Gross amounts recognized	[1]	6,157	8,252
Derivative liabilities, Gross amounts offset on the balance sheet	[1]	0	0
Derivative liabilities, Net amounts presented on the balance sheet	[1],[2],[3]	6,157	8,252
Derivative liabilities, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(4,348)	(6,033)
Derivative liabilities, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	(748)	(933)
Derivative liabilities, Net amounts	[1]	1,061	1,286
Payables under repurchase agreements, Gross amounts recognized	[1]	22,278	18,607
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]	22,278	18,607
Payables under repurchase agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(21,471)	(17,979)
Payables under repurchase agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[4]	0	0
Payables under repurchase agreements, Net amounts	[1]	807	628
Payables under securities lending transactions, Gross amounts recognized	[1]	1,441	1,208
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]	1,441	1,208
Payables under securities lending transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[4],[5]	(1,221)	(953)
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]	220	255
Financial liabilities, Gross amounts recognized, Total	[1]	29,876	28,067
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]	29,876	28,067
Financial liabilities, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[4],[5]	(27,040)	(24,965)
Financial liabilities, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[4]	(748)	(933)
Financial liabilities, Net amounts, Total	[1]	¥ 2,088	¥ 2,169
[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 ¥8,168 billion and ¥7,652 billion, respectively, at March 31, 2021, and ¥6,256 billion and ¥5,808 billion, respectively, at September 30, 2021.
[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 ¥10,551 billion and ¥18,321 billion, respectively, at March 31, 2021, and ¥15,957 billion and ¥21,817 billion, respectively, at September 30, 2021.
[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 ¥2,694 billion and ¥958 billion, respectively, at March 31, 2021, and ¥2,408 billion and ¥1,229 billion, respectively, at September 30, 2021.

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	Sep. 30, 2021	Mar. 31, 2021
Offsetting Financial Assets And Financial Liabilities [Line Items]
Receivables under resale agreement subject to enforceable master netting arrangements	¥ 15,957	¥ 10,551
Payables under repurchase agreement subject to enforceable master netting arrangements	21,817	18,321
Receivables under securities transaction borrowing subject to master netting arrangement	2,408	2,694
Payables under securities transaction lending subject to master netting arragement	1,229	958
Subject To Enforceable Master Netting Arragement [Member]
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets subject to enforceable master netting arrangements	6,256	8,168
Derivative liabilities subject to enforceable master netting arrangements	¥ 5,808	¥ 7,652

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	Sep. 30, 2021	Mar. 31, 2021
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	¥ 22,278	¥ 18,607
Securities lending transactions	1,441	1,208
Total	23,719	19,815
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	14,303	9,459
Securities lending transactions	1,093	943
Total	15,396	10,402
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	3,151	3,586
Securities lending transactions	136	15
Total	3,287	3,601
31 to 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	3,082	4,315
Securities lending transactions	12
Total	3,094	4,315
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	1,742	1,247
Securities lending transactions	200	250
Total	¥ 1,942	¥ 1,497

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	Sep. 30, 2021	Mar. 31, 2021
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	¥ 22,278	¥ 18,607
Securities lending transactions	1,441	1,208
Japanese government bonds and Japanese local government bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	2,767	1,787
Securities lending transactions	234	352
Foreign government bonds and foreign agency mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	18,339	15,917
Securities lending transactions	153	131
Commercial Paper and Corporate Bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	264	284
Securities lending transactions	52	57
Equity Securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	838	544
Securities lending transactions	989	654
Other securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	70	75
Securities lending transactions	¥ 13	¥ 14

Business Segment Information -

Business Segment Information - Additional Information (Detail)	6 Months Ended
	Sep. 30, 2021Segment
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		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	[1],[2]	¥ 1,130.6	¥ 1,093.3
General and administrative expenses	[1],[3]	680.9	679.3
Equity in earnings (losses) of equity method investees—net	[1]	16.5	11.5
Amortization of goodwill and others	[1]	5.8	6.1
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	460.4	419.4
Fixed assets	[1],[5]	1,722.3	1,721.3
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]	345.9	314.2
General and administrative expenses	[1],[3]	311.3	313.5
Equity in earnings (losses) of equity method investees—net	[1]	5.5	3.5
Amortization of goodwill and others	[1]	1.1	1.1
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	39	3.1
Fixed assets	[1],[5]	538.6	516.2
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]	230.1	226.6
General and administrative expenses	[1],[3]	99.3	104
Equity in earnings (losses) of equity method investees—net	[1]	2.3	2.4
Amortization of goodwill and others	[1]	0	0.1
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	133.1	124.9
Fixed assets	[1],[5]	182.5	195.7
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]	250	226
General and administrative expenses	[1],[3]	126.2	125.2
Equity in earnings (losses) of equity method investees—net	[1]	7.4	5.9
Amortization of goodwill and others	[1]	0.2	0.2
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	131	106.5
Fixed assets	[1],[5]	166.7	162.8
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]	253.7	293
General and administrative expenses	[1],[3]	107.5	105.3
Equity in earnings (losses) of equity method investees—net	[1]	0
Amortization of goodwill and others	[1]	0.4	0.4
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	145.8	187.3
Fixed assets	[1],[5]	96.3	95.6
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]	29	23.8
General and administrative expenses	[1],[3]	16.2	15.7
Equity in earnings (losses) of equity method investees—net	[1]	0.8	0.4
Amortization of goodwill and others	[1]	3.6	3.8
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4]	10	4.7
Fixed assets	[1],[5]	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]	21.9	9.7
General and administrative expenses		20.4	15.6
Equity in earnings (losses) of equity method investees—net		0.5	(0.7)
Amortization of goodwill and others	[1],[6]	0.5	0.5
Net business profits (losses) + Net gains (losses) related to ETFs and others	[1],[4],[6]	1.5	(7.1)
Fixed assets		¥ 738.2	¥ 751
[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 six months ended September 30, 2020 and 2021, net gains (losses) related to ETFs and others amounted to ¥(19.0) billion and ¥21.8 billion, respectively, of which ¥(20.4) billion and ¥22.9 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 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		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others	[1],[2]	¥ 1,130.6	¥ 1,093.3
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		21.8	(19)
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		¥ 22.9	¥ (20.4)
[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 six months ended September 30, 2020 and 2021, net gains (losses) related to ETFs and others amounted to ¥(19.0) billion and ¥21.8 billion, respectively, of which ¥(20.4) billion and ¥22.9 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 Millions	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
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	¥ 460,400	¥ 419,400
Adjustment to reconcile management reporting to Japanese GAAP:
General and administrative expenses: non-allocated gains (losses), net	19,200	4,100
Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans)	(59,900)	(84,800)
Gains on reversal of reserves for possible losses on loans, and others	10,200	3,600
Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others	(6,900)	(50,500)
Net extraordinary gains (losses)	47,300	65,800
Others	(23,700)	(24,200)
Income before income tax expense under Japanese GAAP	446,600	333,400
Adjustment to reconcile Japanese GAAP to U.S. GAAP:
Derivative financial instruments and hedging activities	(47,900)	(12,900)
Investments	13,800	285,400
Loans	2,200	(10,800)
Allowances for credit losses	5,000	35,800
Premises and equipment	(34,900)	(37,100)
Land revaluation	1,600	2,700
Business combinations	3,400	(4,300)
Pension liabilities	(63,900)	(84,500)
Consolidation of variable interest entities	51,100	36,600
Foreign currency translation	2,400	(200)
Others	3,800	3,700
Income before income tax expense	¥ 383,200	¥ 547,841

Business Segment Information _4

Business Segment Information (Reconciliation of Assets from Segment to Consolidated) (Detail) - JPY (¥) ¥ in Billions		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Schedule Of Assets By Segment [Line Items]
Fixed assets	[1],[2]	¥ 1,722.3	¥ 1,721.3
U.S. GAAP adjustments	[3]	763.6	818.4
Premises and equipment-net, Goodwill, Intangible assets, and right-of-use assets related to operating leases included in Other assets		¥ 2,485.9	¥ 2,539.7
[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.