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 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 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 | — | — | — | — | 
                                                38,069,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                10,531,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,322,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,805,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                42,240,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,807,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,894,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,471,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                5,446,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,245,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,173,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,263,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,794,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,785,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,945,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,451,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,284,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,906,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,773,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,699,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,033,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,176,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                8,080,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,080,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,080,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,080,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,080,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,732,897
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,732,897
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                9,732,897
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                13,232,897
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                13,232,897
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | 
                                                56,216,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                40,234,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                52,667,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,307,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                41,493,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                28,405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,103,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                25,349,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                62,775,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                42,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                60,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,173,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                31,524,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,599,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                47,061,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,790,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,155,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                28,639,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                6,255.78
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,533.63
                                                
                                             | — | — | — | — | 
                                                5,869.59
                                                
                                             | 
                                                4,262.98
                                                
                                             | — | 
                                                3,366.09
                                                
                                             | 
                                                5,276.10
                                                
                                             | — | — | — | 
                                                4,647.02
                                                
                                             | 
                                                3,222.09
                                                
                                             | 
                                                4,264.58
                                                
                                             | — | — | 
                                                2,860.17
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                70.00
                                                
                                             | 
                                                60.00
                                                
                                             | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | 
                                                47.50
                                                
                                             | — | — | — | — | 
                                                30.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                30.00
                                                
                                             | 
                                                30.00
                                                
                                             | — | — | — | 
                                                30.00
                                                
                                             | — | — | — | 
                                                22.50
                                                
                                             | — | — | — | — | 
                                                15.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                446.47
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                313.94
                                                
                                             | 
                                                934.73
                                                
                                             | 
                                                390.14
                                                
                                             | — | — | 
                                                192.64
                                                
                                             | — | — | 
                                                523.94
                                                
                                             | 
                                                458.01
                                                
                                             | 
                                                287.10
                                                
                                             | — | — | — | 
                                                371.05
                                                
                                             | 
                                                79.41
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | 
                                                440.12
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                309.48
                                                
                                             | 
                                                917.62
                                                
                                             | 
                                                383.00
                                                
                                             | — | — | 
                                                192.47
                                                
                                             | — | — | 
                                                523.49
                                                
                                             | 
                                                457.20
                                                
                                             | 
                                                286.60
                                                
                                             | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.880
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.948
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.863
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.937
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.942
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.853
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.871
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.954
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.830
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.878
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.074
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.245
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.064
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.141
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.021
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                9.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                13.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                25.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                9.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                11.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                52.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.223
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.064
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.311
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.081
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                7,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                8,231,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,761,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,046,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,921,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                -6,887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -4,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -2,581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,576,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,966,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                -828,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -965,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -765,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,053,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -12,770,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                24,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                24,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                20,753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,825,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,678,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                88
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,222
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,478
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                221
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                165
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                304
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                648
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                64
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                114
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                50
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                327
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,521
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                344
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,527
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,420
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                327
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,563
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                358
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                154
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                49
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                40
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                83
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                185
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                214
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                178
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                53
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2.166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3.560
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2.369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.317
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.969
                                                
                                                    
                                                        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
                                                    
                                                
                                             |