Financial risk management - Summary of Price Sensitivity Analysis (Detail) - Trading equity securities [member] - Equity price risk [member] - JPY (¥) ¥ in Millions		12 Months Ended
Apr. 01, 2020	Mar. 31, 2022	Mar. 31, 2021
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, assets [line items]
Income before income taxes	¥ (8,439)	¥ (11,604)	¥ (17,930)
Other comprehensive income (before considering the tax effect)	¥ (769)	¥ (9,871)	¥ (23,598)
Decreased market prices of marketable equity instruments	10.00%	10.00%	10.00%

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

No definition available.

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- Definition

The amount of increase (decrease) in the fair value measurement of assets, recognised in other comprehensive income before tax, due to a reasonably possible decrease in an unobservable input. [Refer: Tax income (expense)]

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The amount of increase (decrease) in the fair value measurement of assets, recognised in profit or loss before tax, due to a reasonably possible decrease in an unobservable input. [Refer: Tax income (expense)]

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The percentage of a reasonably possible decrease in an unobservable input used in fair value measurement of assets.

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