Key Financial Data Of Group
| Concept | As at 2025-03-31 | 2024-04-01 to 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 | — | 
                                                16,838,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,844,622,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,309,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,936,064,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,266,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,674,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,687,595,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,092,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,287,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,321,971,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                815,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                732,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                596,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                989,719,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                232,261,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                568,627,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                565,403,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                718,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                727,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                810,618,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | 
                                                569,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                704,543,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                420,591,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                549,088,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                569,757,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | 
                                                546,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                944,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                594,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                636,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                758,072,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | 
                                                15,614,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,147,034,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                15,262,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,918,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,516,386,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,433,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,028,056,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,472,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,509,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,188,748,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                22,040,420,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,145,582,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                21,659,301,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,038,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,178,389,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,502,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                19,231,006,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,348,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,105,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                18,500,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                1,759.68
                                                
                                             | — | 
                                                1,594.34
                                                
                                             | — | — | — | 
                                                1,720.08
                                                
                                             | 
                                                1,568.53
                                                
                                             | — | 
                                                1,523.27
                                                
                                             | 
                                                1,626.59
                                                
                                             | — | — | — | 
                                                1,554.65
                                                
                                             | 
                                                1,493.05
                                                
                                             | 
                                                1,497.13
                                                
                                             | — | — | 
                                                1,461.62
                                                
                                             | 
| Basic earnings (loss) per share | — | 
                                                64.19
                                                
                                             | — | 
                                                60.24
                                                
                                             | 
                                                49.10
                                                
                                             | 
                                                79.40
                                                
                                             | — | — | 
                                                16.81
                                                
                                             | — | — | 
                                                47.28
                                                
                                             | 
                                                44.78
                                                
                                             | 
                                                60.85
                                                
                                             | — | — | — | 
                                                54.16
                                                
                                             | 
                                                63.14
                                                
                                             | — | 
| Diluted earnings per share | — |  | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | 
                                                0.708
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.702
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.705
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.695
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.704
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.704
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.729
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.734
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.707
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.713
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.011
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.029
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.030
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.040
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.043
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                9.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                29.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                10.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                9.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                294,904,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,274,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,129,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                434,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,190,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -864,578,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -193,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -496,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -590,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                230,004,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -217,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -135,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -200,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -125,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -129,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                4,891,829,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,634,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,650,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,207,150,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,490,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                498
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                304
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                507
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                313
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                501
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                498
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                489
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                303
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |