Key Financial Data Of Group
| Concept | 2024-01-01 to 2024-03-31 | As at 2024-03-31 | 2023-10-01 to 2024-03-31 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | 2023-01-01 to 2023-03-31 | As at 2023-03-31 | 2022-10-01 to 2023-03-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Net sales | — | — | 
                                                5,170,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,615,805,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,949,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | — | 
                                                540,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                830,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                624,095,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                366,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                570,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                429,102,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | — | — | 
                                                366,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                570,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                428,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | — | 
                                                4,185,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,905,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,739,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | — | 
                                                6,518,023,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,419,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,203,551,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | 
                                                15.83
                                                
                                             | — | 
                                                34.32
                                                
                                             | — | 
                                                53.96
                                                
                                             | 
                                                20.88
                                                
                                             | — | 
                                                40.59
                                                
                                             | 
| Diluted earnings per share | — | — |  | — |  | — | — | 
                                                40.43
                                                
                                             | 
| Equity-to-asset ratio | — | 
                                                0.642
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.608
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.601
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                676,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                445,581,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                444,378,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | — | 
                                                30,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -242,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -114,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -287,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -78,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -121,862,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | — | 
                                                2,206,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,787,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,868,384,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |