v3.26.1
Fair Value of Financial Assets and Liabilities - Summary of Aggregate Deferred Day One Profit (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of detailed information about financial instruments [abstract]    
Balance at beginning of period ¥ 11,030 ¥ 12,173
Increase due to new trades 6,970 6,936
Reduction due to redemption, sales or passage of time (7,122) (8,079)
Balance at end of period ¥ 10,878 ¥ 11,030