Key Financial Data Of Reporting Company
| Concept | As at 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | As at 2021-12-31 | As at 2021-12-31 | 2021-01-01 to 2021-12-31 | As at 2020-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||
| Business results of reporting company | |||||||||||||||
| Net sales | — | — | 
                                                6,581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,015,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,118,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                823,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                433,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                -1,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,586,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,720,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,430,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | 
                                                2,144,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,285,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,497,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,308,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | 
                                                47,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                46,807,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                41,335,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                41,036,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                40,220,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | 
                                                89,902,858
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                89,446,777
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                81,923,230
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                81,518,316
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                80,596,128
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                68,055,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                65,200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                57,544,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                58,470,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                61,504,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                136,127,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                142,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                89,385,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                94,349,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                78,886,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                754.41
                                                
                                             | — | — | — | — | 
                                                726.29
                                                
                                             | — | — | 
                                                699.45
                                                
                                             | 
                                                714.03
                                                
                                             | — | — | — | — | 
                                                754.79
                                                
                                             | 
| Dividend paid per share | — | — |  |  | — | — | — |  | — | — | — |  | — |  | — | 
| Interim dividend paid per share | — | — |  |  | — | — | — |  | — | — | — |  | — |  | — | 
| Basic earnings (loss) per share | — | — | 
                                                23.89
                                                
                                             | 
                                                -39.81
                                                
                                             | — | — | — | 
                                                -18.30
                                                
                                             | — | — | — | 
                                                -52.47
                                                
                                             | — | 
                                                -16.62
                                                
                                             | — | 
| Diluted earnings per share | — | — | 
                                                19.63
                                                
                                             |  | — | — | — |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | 
                                                0.498
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.457
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.641
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.617
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.771
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.0323
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                43.87
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Number of employees | 
                                                58
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                374
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                350
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                198
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                190
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                1.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                62.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                69.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                12.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | 
                                                0.483
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.655
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.985
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.877
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.829
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | 
                                                1.618
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.375
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.099
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.157
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |