Key Financial Data Of Group
| Concept | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | As at 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | — | 
                                                1,024,281,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,516,848,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,210,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | 
                                                -28,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                298,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                112,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) attributable to owners of parent | — | 
                                                -36,890,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                156,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                83,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | — | 
                                                -73,564,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                186,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,474,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                4,038,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,158,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,005,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                5,570,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,762,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,899,719,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                -15.88
                                                
                                             | — | 
                                                67.51
                                                
                                             | — | 
                                                36.00
                                                
                                             | 
| Diluted earnings per share | — |  | — |  | — |  | 
| Equity-to-asset ratio | 
                                                0.725
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.722
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.679
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — |