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 | 
                                                548,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                794,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                554,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                25,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -149,503,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -67,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                20,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -289,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -76,430,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                20,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -289,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -76,430,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                1,099,205,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,078,616,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,291,917,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                1,434,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,434,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,629,938,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                2.21
                                                
                                             | — | 
                                                -0.67
                                                
                                             | — | 
                                                -31.10
                                                
                                             | — | 
                                                -8.20
                                                
                                             | 
                                                6.41
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.766
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.752
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.793
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |