Revenue from services provided to customers - Additional information (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Revenue from performance obligations satisfied in previous periods	¥ 1,337	¥ 2,151
Remaining performance obligations, Transaction price	¥ 208		¥ 550

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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