Key Financial Data Of Reporting Company
| Concept | 2024-01-01 to 2024-06-30 | As at 2024-06-30 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-06-30 | As at 2023-06-30 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | 
                                                6,322,401,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,397,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,011,025,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                199,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                126,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                32,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                2,866,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,767,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,755,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                7,347,174,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,281,524,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,565,672,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                13.74
                                                
                                             | — | 
                                                8.13
                                                
                                             | — | 
                                                -0.24
                                                
                                             | — | 
| Diluted earnings per share | 
                                                13.66
                                                
                                             | — | 
                                                8.03
                                                
                                             | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.373
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.357
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                158,074,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                393,624,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                359,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -18,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,024,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,849,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                -211,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -384,379,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,552,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,452,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,524,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,888,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |