| Cover | Aug. 19, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 19, 2024 |
| Entity File Number | 333-277828 |
| Entity Registrant Name | EWSB BANCORP, INC. |
| Entity Central Index Key | 0002013792 |
| Entity Tax Identification Number | 00-0000000 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 109 West Second Street |
| Entity Address, City or Town | Kaukauna |
| Entity Address, State or Province | WI |
| Entity Address, Postal Zip Code | 54130 |
| City Area Code | 920 |
| Local Phone Number | 766-4646 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
