Key Financial Data Of Group
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 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 | 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 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 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 | — | — | — | 
                                                62,867,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                37,604,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                38,740,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,231,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                39,766,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                67,135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                37,877,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,780,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                37,122,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,183,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | 
                                                3,875,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                2,240,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,568,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,788,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,653,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,778,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,021,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,330,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                209,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | 
                                                3,247,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,040,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,783,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,306,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                408,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | 
                                                3,030,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,919,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,698,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,403,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,196,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | 
                                                36,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,546,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                34,568,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,707,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                19,516,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,298,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                26,145,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,531,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,677,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | 
                                                87,369,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                67,063,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                85,844,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                67,262,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                71,395,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                88,753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                83,725,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                69,636,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                84,135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                69,584,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | 
                                                2,352.84
                                                
                                             | — | 
                                                1,446.03
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,186.73
                                                
                                             | 
                                                1,373.18
                                                
                                             | — | — | 
                                                1,224.56
                                                
                                             | 
                                                1,947.84
                                                
                                             | — | — | 
                                                1,581.75
                                                
                                             | 
                                                1,025.36
                                                
                                             | 
                                                1,447.81
                                                
                                             | — | — | 
                                                973.21
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | 
                                                205.77
                                                
                                             | — | — | — | — | — | — | 
                                                164.03
                                                
                                             | — | — | — | 
                                                110.02
                                                
                                             | 
                                                128.10
                                                
                                             | — | — | 
                                                156.66
                                                
                                             | 
                                                234.88
                                                
                                             | — | — | 
                                                66.30
                                                
                                             | 
                                                81.08
                                                
                                             | — | — | — | 
                                                -202.88
                                                
                                             | 
                                                25.33
                                                
                                             | — | 
| Diluted earnings per share | — | — | — |  | — | — | — | — | — | — |  | — | — | — |  |  | — | — |  |  | — | — |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | 
                                                0.420
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.336
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.403
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.323
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.273
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.350
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.305
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.237
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.277
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.225
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | 
                                                0.091
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.117
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.085
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.062
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.140
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.066
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.054
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.019
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | 
                                                5.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                7.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                13.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                13.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                48.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | 
                                                2,416,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,432,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,915,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,834,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | 
                                                -1,645,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                -301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,693,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,503,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -396,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | 
                                                -31,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                -3,966,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -2,289,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,679,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                5,962,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                5,730,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,425,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,086,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                103
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                528
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                722
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                416
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                301
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                194
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                197
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,488
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                530
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,519
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,561
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                531
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,589
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                522
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                31
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                317
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                97
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                120
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                108
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                48
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                343
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                107
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                358
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                100
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                112
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |