Key Financial Data Of Group
| Concept | As at 2024-12-31 | As at 2024-12-31 | 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 | 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 | — | — | — | 
                                                6,552,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,868,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,256,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,456,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,352,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | 
                                                987,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                948,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                562,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                651,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                206,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                492,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -261,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                43,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | 
                                                669,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -295,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Comprehensive income | — | — | — | — | 
                                                664,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                404,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -296,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -287,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net assets | — | 
                                                1,222,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,222,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                392,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                392,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                943,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                771,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                2,754,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,767,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,786,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,233,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,215,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,723,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,249,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,230,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                633.98
                                                
                                             | — | — | — | — | — | 
                                                633.98
                                                
                                             | — | 
                                                241.12
                                                
                                             | — | 
                                                241.12
                                                
                                             | 
                                                -148.07
                                                
                                             | — | 
                                                -148.07
                                                
                                             | — | — | 
                                                889.16
                                                
                                             | 
                                                456.60
                                                
                                             | — | — | 
                                                750.74
                                                
                                             | — | 
                                                727.42
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | 
                                                614.17
                                                
                                             | 
                                                614.17
                                                
                                             | — | — | — | 
                                                368.95
                                                
                                             | — | 
                                                368.95
                                                
                                             | — | — | 
                                                -282.13
                                                
                                             | — | 
                                                -714.69
                                                
                                             | 
                                                137.53
                                                
                                             | — | — | 
                                                -271.71
                                                
                                             | 
                                                13.25
                                                
                                             | — | 
                                                36.57
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | 
                                                490.40
                                                
                                             | 
                                                490.40
                                                
                                             | — | — | — | 
                                                298.26
                                                
                                             | — | 
                                                298.26
                                                
                                             | — | — |  | — |  |  | — | — |  |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.444
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.442
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.293
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.289
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.176
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.447
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.281
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.637
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.627
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | 
                                                0.659
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.659
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.676
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.676
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.674
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                -1.130
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.155
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.459
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.018
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.049
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | 
                                                12.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                11.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -5.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                -2.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -6.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                152.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                55.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                402,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                354,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -33,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                62,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -11,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                -117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -125,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -88,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -69,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                -318,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                209,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -72,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | 
                                                1,264,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,279,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,122,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                590,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                407,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                182
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                230
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                213
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                187
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                142
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                127
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                162
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |