Employees
| Concept | As at 2024-01-31 | As at 2023-01-31 | As at 2022-01-31 | As at 2021-01-31 | As at 2020-01-31 | 
|---|---|---|---|---|---|
| Employees | |||||
| Information about reporting company | |||||
| Information about employees of reporting company | |||||
| Number of employees | 
                                                1,321
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,276
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,180
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,079
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,002
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | 
                                                30.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
| Average length of service (Years) | 
                                                6.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
| Average annual salary | 
                                                4,625,682
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — |