v3.26.1
Supplemental cash flow information (Details) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Mar. 14, 2025
Changes in liabilities arising from financing activities [abstract]        
Liabilities arising from financing activities at beginning of period ¥ 2,028 ¥ 1,661 ¥ 350  
Proceeds from short-term loans payable 3,000 1,800 1,200  
Repayments of short-term loans payable (3,041) (1,800) (1,200)  
Repayments of lease obligations   (463) (327)  
Repayments of lease obligations (378) (463) (327)  
Proceeds from loan from related party 19,376 8,508 0  
Repayments of loan from related party (17,758) (7,887) 0  
Total changes from financing cash flows 1,200 158 (327)  
Modification of lease term   79 (81)  
New lease contracts   130 1,719  
Increase by business combination 275      
Interest expense 161 31 5  
Interest paid (153) (31) (5)  
Foreign currency translation (166)      
Total liability-related other changes 449 209 1,638  
Liabilities arising from financing activities at end of period 3,677 2,028 1,661  
Right-of-use assets obtained in exchange for lease liabilities 1,638 79 11  
Intangible assets 2,347      
Next Finance Tech Co, Ltd.        
Changes in liabilities arising from financing activities [abstract]        
Intangible assets       ¥ 5
Ordinary shares of Coincheck Parent       ¥ 1,077
Aplo and 3iQ        
Changes in liabilities arising from financing activities [abstract]        
Ordinary shares of Coincheck Parent 13,935      
Loans        
Changes in liabilities arising from financing activities [abstract]        
Liabilities arising from financing activities at beginning of period 751 0 0  
Proceeds from short-term loans payable 3,000 1,800 1,200  
Repayments of short-term loans payable (3,041) (1,800) (1,200)  
Repayments of lease obligations   0 0  
Repayments of lease obligations 0      
Proceeds from loan from related party 19,376 8,508    
Repayments of loan from related party (17,758) (7,759)    
Total changes from financing cash flows 1,577 749 0  
Modification of lease term   0 0  
New lease contracts   2 0  
Increase by business combination 264      
Interest expense 153 21 0  
Interest paid (145) (21) 0  
Foreign currency translation (166)      
Total liability-related other changes 438 2 0  
Liabilities arising from financing activities at end of period 2,767 751 0  
Promissory note- related party        
Changes in liabilities arising from financing activities [abstract]        
Liabilities arising from financing activities at beginning of period 0 0 0  
Proceeds from short-term loans payable 0 0 0  
Repayments of short-term loans payable 0 0 0  
Repayments of lease obligations   0 0  
Repayments of lease obligations 0      
Proceeds from loan from related party 0 0    
Repayments of loan from related party 0 (128)    
Total changes from financing cash flows 0 (128) 0  
Modification of lease term   0 0  
New lease contracts   128 0  
Increase by business combination 0      
Interest expense 0 0 0  
Interest paid 0 0 0  
Foreign currency translation 0      
Total liability-related other changes 0 128 0  
Liabilities arising from financing activities at end of period 0 0 0  
Lease liabilities        
Changes in liabilities arising from financing activities [abstract]        
Liabilities arising from financing activities at beginning of period 1,277 1,661 350  
Proceeds from short-term loans payable 0 0 0  
Repayments of short-term loans payable 0 0 0  
Repayments of lease obligations   (463) (327)  
Repayments of lease obligations (378)      
Proceeds from loan from related party 0 0    
Repayments of loan from related party 0 0    
Total changes from financing cash flows (378) (463) (327)  
Modification of lease term   79 (81)  
New lease contracts   0 1,719  
Increase by business combination 11      
Interest expense 8 10 5  
Interest paid (8) (10) (5)  
Foreign currency translation 0      
Total liability-related other changes 11 79 1,638  
Liabilities arising from financing activities at end of period ¥ 910 ¥ 1,277 ¥ 1,661