v3.26.1
Financial risk management - Summary of Price Sensitivity Analysis (Detail) - Trading equity securities [member] - Equity price risk [member] - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, assets [line items]    
Income before income taxes ¥ (44,693) ¥ (47,269)
Other comprehensive income (before considering the tax effects) ¥ (14,854) ¥ (8,114)
Decreased market prices of marketable equity instruments 10.00% 10.00%