v3.26.1
Provisions (Details) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Reconciliation of changes in other provisions [abstract]    
Provisions made during the year ¥ 0 ¥ 339
Non-current portion 342 340
Asset retirement obligations    
Reconciliation of changes in other provisions [abstract]    
Other provisions at beginning of period 340 120
Provisions used during the year 0 (120)
Unwind of discount 2 1
Current portion 0 0
Non-current portion 342 340
Other provisions at end of period ¥ 342 ¥ 340