Key Financial Data Of Group
| Concept | 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 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 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 | — | — | 
                                                34,293,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                33,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                31,477,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,726,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                30,262,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                31,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,448,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                25,316,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                26,827,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                1,235,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,046,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,049,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,066,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                993,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,044,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                875,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                108,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                138,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                1,034,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                906,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                832,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                599,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                208,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                1,516,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                1,414,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                953,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,074,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                555,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                24,022,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,476,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                22,831,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,926,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                21,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,713,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                21,085,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,544,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,044,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                20,162,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                44,081,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                43,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                43,197,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                41,729,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,006,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                41,578,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                41,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,377,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                39,888,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                4,064.74
                                                
                                             | — | — | 
                                                3,803.13
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                3,863.02
                                                
                                             | 
                                                3,709.80
                                                
                                             | — | 
                                                3,567.93
                                                
                                             | 
                                                3,673.56
                                                
                                             | — | — | — | 
                                                3,567.09
                                                
                                             | 
                                                3,475.64
                                                
                                             | 
                                                3,401.27
                                                
                                             | — | — | 
                                                3,410.84
                                                
                                             | 
| Basic earnings (loss) per share | — | — | 
                                                175.04
                                                
                                             | — | — | — | — | — | — | — | 
                                                152.30
                                                
                                             | — | 
                                                156.67
                                                
                                             | 
                                                153.32
                                                
                                             | — | — | 
                                                132.99
                                                
                                             | — | — | 
                                                140.87
                                                
                                             | 
                                                96.79
                                                
                                             | 
                                                101.68
                                                
                                             | — | — | — | 
                                                15.65
                                                
                                             | 
                                                35.25
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — | — | — | — | — | — |  | — |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.545
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                0.529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.507
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.499
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.496
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.0442
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.0405
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0431
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0407
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0378
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0389
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0281
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0291
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0046
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                7.75
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                8.91
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.74
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                57.56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25.56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                1,133,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                1,369,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                583,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                764,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -697,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                -462,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -617,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,002,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -968,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -132,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                -283,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -390,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -221,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                363,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                3,330,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,025,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,392,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,141,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                78
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                899
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                392
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                749
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                287
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                78
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                339
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                894
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                742
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                735
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                901
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                920
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                703
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                921
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                706
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                37
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                81
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                90
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                55
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |