Key Financial Data Of Group
| Concept | 2024-10-01 to 2025-03-31 | As at 2025-03-31 | As at 2024-09-30 | 2023-10-01 to 2024-09-30 | 2023-10-01 to 2024-03-31 | As at 2024-03-31 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | 
                                                6,884,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,951,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,170,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                551,076,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                534,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                539,411,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                351,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                341,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                365,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                360,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                341,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                365,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                4,465,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,160,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,184,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                10,419,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,394,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,518,023,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                32.89
                                                
                                             | — | — | 
                                                31.96
                                                
                                             | 
                                                34.23
                                                
                                             | — | 
| Diluted earnings per share |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.425
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.651
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.642
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                965,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                280,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                676,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -2,447,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                2,671,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -387,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -287,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,878,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,686,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,206,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |