Employee benefits - Summary of Employee Benefit Expense (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Disclosure of Detailed Information About Employee Benefits Expense [Line Items]
Total employee benefits expenses	¥ 1,840,803	¥ 1,743,936	¥ 1,539,965

The expense of all forms of consideration given by an entity in exchange for a service rendered by employees or for the termination of employment.

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