Earnings per Share - Schedule of Basis for Calculating Basic and Diluted Earnings per Share (Details) - JPY (¥) ¥ / shares in Units, shares in Thousands, ¥ in Millions	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Earnings per share [abstract]
Net profit (loss) for the year attributable to owners of the Company JPY (millions)	¥ (152,390)	¥ 107,928	¥ 144,067
Net profit (loss) used for calculation of earnings per share JPY (millions)	¥ (152,390)	¥ 107,928	¥ 144,067
Weighted-average number of ordinary shares outstanding during the year (basic) (in shares)	1,575,062	1,578,873	1,564,450
Dilutive effect (in shares)	0	26,450	15,893
Weighted-average number of ordinary shares outstanding during the year (diluted) (in shares)	1,575,062	1,605,323	1,580,343
Basic earnings per share (in JPY per share)	¥ (96.75)	¥ 68.36	¥ 92.09
Diluted earnings per share (in JPY per share)	¥ (96.75)	¥ 67.23	¥ 91.16

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

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The profit (loss) attributable to ordinary equity holders of the parent entity, adjusted for the effects of all dilutive potential ordinary shares. [Refer: Profit (loss)]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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