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 | 
                                                33,718,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                34,343,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                7,388,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,418,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                5,160,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,772,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,568,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                5,949,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,881,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,774,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                55,948,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,413,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,309,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                102,773,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                94,937,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                91,728,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                41.35
                                                
                                             | — | 
                                                -0.74
                                                
                                             | — | 
                                                30.35
                                                
                                             | — | 
                                                28.73
                                                
                                             | 
                                                20.89
                                                
                                             | 
| Diluted earnings per share | 
                                                41.16
                                                
                                             | — | — | — | 
                                                30.22
                                                
                                             | — | 
                                                28.61
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.542
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.559
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |