Key Financial Data Of Group
| Concept | 2023-04-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2022-12-31 | 2022-04-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Net sales | 
                                                43,482,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                46,459,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                32,356,890,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                1,949,799,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,998,053,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,176,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                999,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,469,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                723,322,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                2,056,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,971,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,624,435,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                26,728,010,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                25,256,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,967,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                44,823,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                41,175,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                38,246,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                171.85
                                                
                                             | — | 
                                                80.71
                                                
                                             | — | 
                                                246.01
                                                
                                             | — | 
                                                120.38
                                                
                                             | 
                                                52.15
                                                
                                             | 
| Diluted earnings per share | 
                                                166.25
                                                
                                             | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.596
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.613
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.653
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |