Employees
| Concept | As at 2025-02-28 | As at 2025-02-28 | As at 2024-02-29 | As at 2024-02-29 | As at 2023-02-28 | As at 2023-02-28 | As at 2022-02-28 | As at 2022-02-28 | As at 2021-02-28 | As at 2021-02-28 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||
| Information about reporting company | ||||||||||
| Information about employees of reporting company | ||||||||||
| Number of employees | 
                                                302
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                402
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                300
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                264
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                209
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                160
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | 
                                                40.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average length of service (Years) | 
                                                4.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average annual salary | 
                                                5,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — |