v3.26.1
Non-trading investments - Summary of AFS debt securities (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
AFS debt securities    
Amortized cost [1] ¥ 276,252 ¥ 108,704
Unrealized gains   19
Unrealized losses (4,908) (1,693)
Fair value 271,344 107,030
Japanese government securities [Member]    
AFS debt securities    
Amortized cost [1] 99,977 25,001
Unrealized losses (493) (187)
Fair value 99,484 24,814
Japanese agency and municipal securities [Member]    
AFS debt securities    
Amortized cost [1] 160,639 81,913
Unrealized gains   19
Unrealized losses (4,129) (1,495)
Fair value 156,510 80,437
Bank and corporate debt securities [Member]    
AFS debt securities    
Amortized cost [1] 15,636 1,790
Unrealized losses (286) (11)
Fair value ¥ 15,350 ¥ 1,779
[1] No allowances for credit losses have been recognized as of March 31, 2025 and 2026.