Key Financial Data Of Group
| Concept | As at 2024-03-31 | 2024-01-01 to 2024-03-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-03-31 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | — | 
                                                1,874,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,256,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,368,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                275,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                562,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                139,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | 
                                                194,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | 
                                                190,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                404,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | 
                                                794,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                505,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                2,445,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,077,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | — | 
                                                179.03
                                                
                                             | 
                                                368.95
                                                
                                             | — | 
                                                103.28
                                                
                                             | — | 
| Diluted earnings per share | — | 
                                                142.53
                                                
                                             | 
                                                298.26
                                                
                                             | — |  | — | 
| Equity-to-asset ratio | 
                                                0.325
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.293
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.243
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |