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 | 
                                                19,467,904,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                25,516,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,039,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                2,899,727,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,121,583,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,424,247,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                1,842,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,564,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,287,005,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                2,897,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,777,073,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,031,988,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                60,667,047,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                57,368,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                58,623,849,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                113,641,276,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                100,403,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                101,669,121,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                36.73
                                                
                                             | — | 
                                                11.96
                                                
                                             | — | 
                                                31.28
                                                
                                             | — | 
                                                45.73
                                                
                                             | 
                                                19.77
                                                
                                             | 
| Diluted earnings per share | 
                                                36.69
                                                
                                             | — | — | — | 
                                                31.21
                                                
                                             | — | 
                                                45.63
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.510
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.545
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.550
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |