Key Financial Data Of Reporting Company
| Concept | 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 | 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 | 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 | As at 2022-03-31 | 2021-04-01 to 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 reporting company | ||||||||||||||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||||||||||||||
| Net sales | — | — | — | — | — | 
                                                153,020,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                108,483,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                106,331,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                146,746,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                89,367,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                128,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,504,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                94,787,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                61,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                93,316,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                18,396,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                15,076,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,812,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,561,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,601,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                511,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                888,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,299,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,194,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                15,903,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,506,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,849,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,139,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -14,957,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | 
                                                12,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                12,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                12,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | 
                                                109,468,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                109,468,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                54,734,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                54,734,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                57,234,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | 
                                                117,862,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                62,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                108,991,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,096,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                56,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                107,915,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                105,160,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                54,998,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                106,030,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                58,182,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                209,316,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                171,403,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                211,386,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                171,857,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                149,471,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                188,623,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                180,389,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                140,877,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                186,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                137,559,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                1,113.36
                                                
                                             | — | — | — | — | — | 
                                                594.94
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,006.80
                                                
                                             | 
                                                521.47
                                                
                                             | — | 
                                                511.98
                                                
                                             | 
                                                974.95
                                                
                                             | — | — | 
                                                948.33
                                                
                                             | — | 
                                                501.70
                                                
                                             | 
                                                956.10
                                                
                                             | — | — | 
                                                530.00
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                57.00
                                                
                                             | 
                                                57.00
                                                
                                             | — | — | — | 
                                                113.00
                                                
                                             | — | — | — | 
                                                113.00
                                                
                                             | — | — | — | — | 
                                                113.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                28.00
                                                
                                             | 
                                                28.00
                                                
                                             | — | — | — | 
                                                56.00
                                                
                                             | — | — | — | 
                                                56.00
                                                
                                             | — | — | — | — | 
                                                56.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                172.56
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                150.97
                                                
                                             | 
                                                107.13
                                                
                                             | 
                                                117.01
                                                
                                             | — | — | 
                                                62.73
                                                
                                             | — | — | 
                                                76.21
                                                
                                             | 
                                                28.76
                                                
                                             | — | 
                                                47.61
                                                
                                             | — | — | 
                                                -134.80
                                                
                                             | 
                                                -169.27
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | 
                                                172.09
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                150.55
                                                
                                             | 
                                                106.90
                                                
                                             | 
                                                116.76
                                                
                                             | — | — | 
                                                62.63
                                                
                                             | — | — | 
                                                76.08
                                                
                                             | 
                                                28.72
                                                
                                             | — | 
                                                47.54
                                                
                                             | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.556
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.363
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                0.509
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.324
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.374
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.564
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.574
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.389
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.558
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.420
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.162
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                0.270
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.117
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.124
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.079
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.056
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.050
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.210
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.157
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                10.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                11.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                34.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                28.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                36.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.378
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.532
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.901
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.964
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | 
                                                24,656,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                26,799,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                24,869,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                18,165,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,755,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | 
                                                -11,445,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                -55,915,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -12,104,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -9,297,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -9,539,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | 
                                                -20,901,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                6,926,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -9,493,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -8,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                41,584,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                49,306,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                71,423,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                68,125,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                67,680,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                88
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,356
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,516
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,934
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                877
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                157
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                88
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,033
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,053
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3,411
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,932
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,880
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,340
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3,369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,878
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,437
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,891
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,143
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,173
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,311
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3,264
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,325
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,050
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                92
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                5,365
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2,978
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,885
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3,038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,956
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,440
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2,191
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | 
                                                1.391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1.503
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.634
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.286
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.528
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | 
                                                2.134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2.168
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.421
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |