Employees
| Concept | As at 2024-09-30 | As at 2024-02-29 | As at 2023-02-28 | As at 2022-02-28 | As at 2021-02-28 | As at 2020-02-29 | 
|---|---|---|---|---|---|---|
| Employees | ||||||
| Information about reporting company | ||||||
| Information about employees of reporting company | ||||||
| Number of employees | 
                                                294
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                290
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                296
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                325
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                375
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                994
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                935
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                797
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                500
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                617
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                820
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | 
                                                38.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
| Average length of service (Years) | 
                                                5.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
| Average annual salary | 
                                                5,335,611
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — |