Employees
| Concept | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | As at 2021-03-31 | As at 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Employees | |||||||||||||
| Information about reporting company | |||||||||||||
| Information about employees of reporting company | |||||||||||||
| Number of employees | 
                                                4,970
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,090
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,692
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,090
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6,662
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6,371
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,895
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,795
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6,015
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,634
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,241
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,112
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                4,482
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,478
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,447
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,478
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8,929
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8,712
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,509
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8,224
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8,391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,652
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8,885
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,748
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | — | — | — | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average age (Months) | — | — | — | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average length of service (Years) | — | — | — | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average length of service (Months) | — | — | — | 
                                                0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Average annual salary | — | — | — | 
                                                5,601,253
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — |