Key Financial Data Of Group
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | |||||||||||||||||||||||||||
| Business results of group | |||||||||||||||||||||||||||
| Net sales | — | — | — | — | 
                                                18,104,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                12,368,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,487,010,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,628,035,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,542,857,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,414,519,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,071,685,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,265,384,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,522,575,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,784,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                -30,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -106,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                206,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                337,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -130,431,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -95,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                153,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                133,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                419,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                454,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | 
                                                -6,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                247,352,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -72,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                69,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                298,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | — | 
                                                -96,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                464,265,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -51,960,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                74,853,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                459,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | 
                                                10,800,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,045,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                10,991,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,186,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,112,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,782,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,960,010,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,335,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,970,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,322,889,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | 
                                                19,094,138,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                15,974,018,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                19,511,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,575,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,475,147,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,359,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                15,867,883,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,610,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,118,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,809,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | 
                                                1,878.94
                                                
                                             | — | — | — | — | — | 
                                                1,751.36
                                                
                                             | — | — | — | — | 
                                                1,918.31
                                                
                                             | 
                                                1,781.95
                                                
                                             | — | 
                                                1,678.68
                                                
                                             | 
                                                1,787.43
                                                
                                             | — | — | — | 
                                                1,754.29
                                                
                                             | 
                                                1,654.38
                                                
                                             | 
                                                1,762.04
                                                
                                             | — | — | 
                                                1,658.02
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                -1.12
                                                
                                             | — | — | — | — | — | 
                                                4.75
                                                
                                             | 
                                                29.86
                                                
                                             | 
                                                41.39
                                                
                                             | — | — | 
                                                -7.15
                                                
                                             | — | — | 
                                                -11.86
                                                
                                             | 
                                                15.42
                                                
                                             | 
                                                11.16
                                                
                                             | — | — | — | 
                                                43.64
                                                
                                             | 
                                                47.99
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — |  | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | 
                                                0.564
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.629
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.562
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.615
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.614
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.586
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.691
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.707
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.777
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.806
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                -0.001
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.003
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.018
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.023
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.004
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.007
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.009
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.006
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.027
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.028
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                111.79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                19.36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.97
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28.02
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                38.71
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                12.44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.31
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                903,073,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,337,851,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -674,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,324,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                848,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                -121,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -1,955,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,405,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -904,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -309,879,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                111,524,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                160,589,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,794,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,791,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,289,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                1,789,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                895,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,350,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,635,679,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,074,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                372
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                402
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                216
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                216
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                107
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                265
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                246
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                229
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                227
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                314
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                254
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                221
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                249
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                216
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                31
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |