Key Financial Data Of Group
| Concept | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 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 | 2022-01-01 to 2022-12-31 | 2021-01-01 to 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | 2021-01-01 to 2021-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | |||||||||||||||||||||
| Business results of group | |||||||||||||||||||||
| Net sales | — | 
                                                257,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                257,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                29,534,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,534,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                59,482,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                59,482,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                115,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                115,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                -780,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -755,076,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -930,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -934,135,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,112,190,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,110,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,063,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,066,450,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,149,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,155,524,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                -806,756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -932,897,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,111,150,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,059,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,114,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Comprehensive income | — | — | 
                                                -810,324,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -931,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,101,467,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,058,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,115,240,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net assets | 
                                                2,124,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,169,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,924,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,894,540,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,212,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,186,828,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,937,869,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,955,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,129,541,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,147,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                2,157,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,275,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,052,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,021,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,398,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,373,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,091,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,108,589,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,279,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,297,368,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                43.57
                                                
                                             | — | — | — | 
                                                44.53
                                                
                                             | — | 
                                                48.44
                                                
                                             | — | 
                                                47.65
                                                
                                             | 
                                                40.71
                                                
                                             | — | 
                                                39.79
                                                
                                             | — | — | 
                                                76.37
                                                
                                             | 
                                                77.09
                                                
                                             | — | — | 
                                                107.13
                                                
                                             | — | 
                                                108.06
                                                
                                             | 
| Basic earnings (loss) per share | — | 
                                                -19.00
                                                
                                             | 
                                                -18.56
                                                
                                             | — | — | 
                                                -26.82
                                                
                                             | — | 
                                                -26.90
                                                
                                             | — | — | 
                                                -43.81
                                                
                                             | — | 
                                                -43.75
                                                
                                             | 
                                                -49.53
                                                
                                             | — | — | 
                                                -49.62
                                                
                                             | 
                                                -68.61
                                                
                                             | — | 
                                                -68.85
                                                
                                             | — | 
| Diluted earnings per share | — |  |  | — | — |  | — |  | — | — |  | — |  |  | — | — |  |  | — |  | — | 
| Equity-to-asset ratio | 
                                                0.959
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.929
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.906
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.904
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.822
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.818
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.898
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.899
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.914
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.914
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -803,403,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -913,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,073,292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -923,688,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -985,354,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -3,155,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -2,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -5,098,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                1,066,994,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,639,492,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                356,315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                815,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,393,651,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | — | — | — | 
                                                1,977,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,720,720,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                994,025,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,703,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,812,360,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |