v3.26.1
Financial risk management - Maturity analysis for financial assets held for managing liquidity risk (Details) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Apr. 01, 2023
Other Financial Liabilities [Abstract]        
Crypto asset borrowings ¥ 37,543 ¥ 44,479    
Borrowing 2,758 751    
Lease liabilities 910 1,277    
Derivative financial liabilities 0 0    
Other 2,051 1,698    
Total Other financial liabilities 5,720 3,727    
Cash and cash equivalents 9,458 8,584 ¥ 10,837 ¥ 7,697
Crypto assets held 37,876 44,680    
Monex Finance Corporation and JSF Trust and Banking Co., Ltd        
Other Financial Liabilities [Abstract]        
Borrowing   751    
Total amount of commitment line borrowing   8,900    
Monex Finance Corporation, JSF Trust and Banking Co., Ltd. and Aozora Bank, Ltd.        
Other Financial Liabilities [Abstract]        
Borrowing 2,524      
Total amount of commitment line borrowing 11,054      
Contractual cash flows        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 37,543 44,479    
Borrowing 2,758 751    
Lease liabilities 919 1,293    
Derivative financial liabilities 0 0    
Other 2,051 1,698    
Total Other financial liabilities 5,729 3,742    
Cash and cash equivalents 9,458 8,584    
Crypto assets held 37,876 44,680    
Within one year        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 37,543 44,479    
Borrowing 2,105 751    
Lease liabilities 366 384    
Derivative financial liabilities 0 0    
Other 2,051 1,698    
Total Other financial liabilities 4,522 2,833    
Cash and cash equivalents 9,458 8,584    
Crypto assets held 37,876 44,680    
From one year to two years        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 0 0    
Borrowing 581 0    
Lease liabilities 356 356    
Derivative financial liabilities 0 0    
Other 0 0    
Total Other financial liabilities 937 356    
Cash and cash equivalents 0 0    
Crypto assets held 0 0    
From two years to three years        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 0 0    
Borrowing 37 0    
Lease liabilities 196 356    
Derivative financial liabilities 0 0    
Other 0 0    
Total Other financial liabilities 233 356    
Cash and cash equivalents 0 0    
Crypto assets held 0 0    
From three years to four years        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 0 0    
Borrowing 37 0    
Lease liabilities 0 197    
Derivative financial liabilities 0 0    
Other 0 0    
Total Other financial liabilities 37 197    
Cash and cash equivalents 0 0    
Crypto assets held 0 0    
From four years to five years        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 0 0    
Borrowing 0 0    
Lease liabilities 0 0    
Derivative financial liabilities 0 0    
Other 0 0    
Total Other financial liabilities 0 0    
Cash and cash equivalents 0 0    
Crypto assets held 0 0    
More than five years        
Other Financial Liabilities [Abstract]        
Crypto asset borrowings 0 0    
Borrowing 0 0    
Lease liabilities 0 0    
Derivative financial liabilities 0 0    
Other 0 0    
Total Other financial liabilities 0 0    
Cash and cash equivalents 0 0    
Crypto assets held ¥ 0 ¥ 0