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 | 
                                                8,243,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,797,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,152,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                2,122,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,722,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,033,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                1,424,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,758,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,294,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                1,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,749,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,293,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                11,427,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,582,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                15,684,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,741,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,535,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                33.62
                                                
                                             | — | 
                                                13.96
                                                
                                             | — | 
                                                41.51
                                                
                                             | — | 
                                                30.54
                                                
                                             | 
                                                12.20
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.729
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.718
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.697
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |