Employees
| Concept | As at 2024-06-30 | As at 2024-06-30 | As at 2024-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2020-06-30 | As at 2020-06-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|
| Employees | |||||||||||
| Information about reporting company | |||||||||||
| Information about employees of reporting company | |||||||||||
| Number of employees | 
                                                413
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                413
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                398
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                404
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                372
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                126
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                126
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                159
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                169
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | — | 
                                                48.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average length of service (Years) | — | 
                                                19.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average annual salary | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — |