Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||
| Net sales | — | — | 
                                                63,351,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                27,084,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,551,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                25,913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                58,422,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,645,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,144,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                23,640,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                50,152,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                3,402,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,143,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,844,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,650,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,724,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,868,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,773,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,776,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,446,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | 
                                                9,478,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,909,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,441,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,359,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,271,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | 
                                                2,960,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,960,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,960,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,960,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,960,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | 
                                                37,054,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                38,054,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                38,054,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                38,054,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                39,254,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                91,781,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                57,770,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                107,944,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                55,726,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                104,250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                98,332,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,466,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                93,746,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                56,387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                105,464,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                69,680,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                121,416,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                65,386,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                65,007,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                115,458,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                109,674,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,839,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                106,051,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                66,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                2,642.64
                                                
                                             | — | — | — | — | 
                                                1,687.91
                                                
                                             | — | — | — | — | 
                                                3,122.47
                                                
                                             | 
                                                1,544.62
                                                
                                             | — | 
                                                1,580.82
                                                
                                             | 
                                                3,015.93
                                                
                                             | — | — | — | 
                                                2,846.39
                                                
                                             | 
                                                1,573.54
                                                
                                             | 
                                                2,646.78
                                                
                                             | — | — | 
                                                1,560.98
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | 
                                                92.00
                                                
                                             | 
                                                128.00
                                                
                                             | — | — | — | 
                                                100.00
                                                
                                             | — | — | — | 
                                                45.00
                                                
                                             | — | — | — | — | 
                                                35.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | 
                                                39.00
                                                
                                             | 
                                                69.00
                                                
                                             | — | — | — | 
                                                43.00
                                                
                                             | — | — | — | 
                                                22.50
                                                
                                             | — | — | — | — | 
                                                10.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | 
                                                52.67
                                                
                                             | — | — | — | — | — | 
                                                271.10
                                                
                                             | 
                                                82.53
                                                
                                             | 
                                                117.88
                                                
                                             | — | — | 
                                                69.26
                                                
                                             | — | — | 
                                                99.15
                                                
                                             | 
                                                65.69
                                                
                                             | 
                                                121.71
                                                
                                             | — | — | — | 
                                                90.58
                                                
                                             | 
                                                113.49
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.8576
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.8291
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.8755
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.8328
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.8572
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.8892
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.8835
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.8554
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.8714
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.8454
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.0182
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.1689
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0528
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0439
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0422
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0446
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0592
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0434
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                45.26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8.79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                32.90
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23.03
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                27.87
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                19.46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23.66
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.77
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                17.94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | 
                                                0.3394
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.5510
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.4438
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.6850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.3864
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                8,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                8,365,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,068,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,441,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,343,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                3,340,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -8,573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -5,001,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,861,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,580,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -6,469,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -4,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -2,443,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -4,686,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                30,236,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                24,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                29,068,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                29,925,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                31,161,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,895
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                190
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                580
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,671
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                607
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,883
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                584
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                586
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,824
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,852
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                592
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,952
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                575
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                246
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                614
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                249
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                581
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                246
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                229
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                630
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                616
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                238
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                639
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                254
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | 
                                                1.833
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.990
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.389
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.076
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.093
                                                
                                                    
                                                        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
                                                    
                                                
                                             |