v3.26.1
Income Tax - Additional Information (Details) - JPY (¥)
 12 Months Ended
Mar. 31, 2027
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Income Tax [Line Items]        
Deferred tax assets, recorded loss   ¥ 0 ¥ 12,772,000,000  
Deductible temporary differences and carryforward of unused tax losses for which deferred tax asset is recognised   0    
Deductible temporary differences related to local taxes   20,194,000,000 103,230,000,000  
Decrease in current tax expense   32,504,000,000 37,159,000,000 ¥ 0
Decrease in deferred tax expense   ¥ 57,536,000,000 ¥ 12,737,000,000 ¥ 0
Japanese statutory effective tax rate   31.46% 31.46% 31.46%
Carryforward of unused tax losses   ¥ 23,268,000,000 ¥ 142,730,000,000  
Deferred tax liabilities   206,000,000 377,000,000  
Deferred tax liabilities recognized   ¥ 0 ¥ 0  
Subsequent Events        
Income Tax [Line Items]        
Japanese statutory effective tax rate 32.34%