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 | 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 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | 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 | — | — | — | — | — | — | 
                                                31,121,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                27,464,976,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,494,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,950,897,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,102,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                25,516,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,868,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,777,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                20,812,140,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,155,122,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | — | 
                                                4,629,102,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,175,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,527,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,175,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,876,431,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,121,583,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,599,130,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,962,181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,510,234,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,617,837,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,303,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,662,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,418,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                636,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,228,376,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | 
                                                6,826,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                6,826,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,826,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,826,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,826,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | 
                                                52,979,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                52,979,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                52,979,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                52,979,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                52,979,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | 
                                                62,594,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,723,580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                60,765,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,927,471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                50,568,411,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                57,368,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                55,306,229,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                49,477,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,964,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,879,652,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | 
                                                108,580,604,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                95,501,716,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                110,461,725,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                97,889,894,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                88,600,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,403,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                102,468,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,450,557,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,429,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                89,380,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | 
                                                1,191.09
                                                
                                             | — | 
                                                1,048.16
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,157.84
                                                
                                             | 
                                                1,034.20
                                                
                                             | — | 
                                                1,009.60
                                                
                                             | 
                                                1,095.16
                                                
                                             | — | — | — | 
                                                1,055.28
                                                
                                             | 
                                                989.19
                                                
                                             | 
                                                1,049.44
                                                
                                             | — | — | 
                                                997.58
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | 
                                                21.00
                                                
                                             | — | — | 
                                                17.00
                                                
                                             | — | — | — | 
                                                14.00
                                                
                                             | — | — | — | 
                                                14.00
                                                
                                             | — | — | — | — | 
                                                14.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | 
                                                9.00
                                                
                                             | — | — | 
                                                7.00
                                                
                                             | — | — | — | 
                                                7.00
                                                
                                             | — | — | — | 
                                                7.00
                                                
                                             | — | — | — | — | 
                                                7.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | — | 
                                                51.27
                                                
                                             | — | — | — | — | 
                                                45.83
                                                
                                             | — | — | 
                                                33.14
                                                
                                             | 
                                                40.27
                                                
                                             | — | — | 
                                                28.35
                                                
                                             | — | — | 
                                                31.28
                                                
                                             | 
                                                12.75
                                                
                                             | 
                                                16.45
                                                
                                             | — | — | — | 
                                                -24.61
                                                
                                             | 
                                                -18.71
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | — | 
                                                51.24
                                                
                                             | — | — | — | — | 
                                                45.80
                                                
                                             | — | — | 
                                                33.11
                                                
                                             | 
                                                40.23
                                                
                                             | — | — | 
                                                28.29
                                                
                                             | — | — | 
                                                31.21
                                                
                                             | 
                                                12.71
                                                
                                             | 
                                                16.39
                                                
                                             | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | 
                                                0.551
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.551
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                0.526
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.530
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.570
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.545
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.514
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.540
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.521
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.557
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | — | 
                                                0.0436
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.0440
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0324
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0357
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0283
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0291
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0156
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                -0.0243
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.0175
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | — | 
                                                11.95
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                13.37
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                18.31
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15.07
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                19.36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17.55
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42.49
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                32.94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.458
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.512
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.493
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.097
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | 
                                                5,239,307,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                784,580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,017,293,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,467,723,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,758,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | 
                                                -3,419,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -3,831,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,198,401,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -449,190,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,704,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | 
                                                -5,656,653,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                5,101,096,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -4,460,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -5,117,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,907,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | 
                                                7,159,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                10,849,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,598,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,612,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,583,181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                123
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                124
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                113
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                119
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                122
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                116
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                115
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | 
                                                1.723
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1.656
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.470
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.417
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.495
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | 
                                                2.134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2.167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.449
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.421
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |