Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||
| Net sales | — | 
                                                63,940,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                40,538,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                33,106,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,496,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,051,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                53,399,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,438,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                26,566,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,140,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                3,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,629,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,078,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,022,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,186,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | 
                                                -2,285,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -10,751,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                979,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,249,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                106,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | 
                                                4,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                4,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | 
                                                34,057,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                34,057,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                34,057,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                34,057,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                34,057,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                26,592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                29,351,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,082,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,975,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,038,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                37,182,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                33,883,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,320,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                33,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                60,175,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                43,569,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                60,447,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,982,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                53,323,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,735,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                57,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                49,113,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                53,375,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                45,447,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                880.63
                                                
                                             | — | 
                                                633.53
                                                
                                             | — | — | — | 
                                                974.29
                                                
                                             | 
                                                799.36
                                                
                                             | — | 
                                                1,129.48
                                                
                                             | 
                                                1,264.63
                                                
                                             | — | — | — | 
                                                1,237.07
                                                
                                             | 
                                                1,127.18
                                                
                                             | 
                                                1,144.45
                                                
                                             | — | — | 
                                                1,068.13
                                                
                                             | 
| Dividend paid per share | — | — | — | 
                                                0.0
                                                
                                             | 
                                                20.0
                                                
                                             | — | — | — | 
                                                20.0
                                                
                                             | — | — | — | 
                                                20.0
                                                
                                             | — | — | — | — | 
                                                20.0
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | 
                                                0.0
                                                
                                             | 
                                                10.0
                                                
                                             | — | — | — | 
                                                11.0
                                                
                                             | — | — | — | 
                                                9.0
                                                
                                             | — | — | — | — | 
                                                9.0
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | 
                                                -25.53
                                                
                                             | — | 
                                                -75.81
                                                
                                             | 
                                                -357.29
                                                
                                             | 
                                                -392.69
                                                
                                             | — | — | 
                                                32.60
                                                
                                             | — | — | 
                                                18.57
                                                
                                             | 
                                                40.50
                                                
                                             | 
                                                29.34
                                                
                                             | — | — | — | 
                                                3.35
                                                
                                             | 
                                                1.95
                                                
                                             | — | 
| Diluted earnings per share | — |  | — |  |  |  | — | — | 
                                                32.54
                                                
                                             | — | — | 
                                                18.53
                                                
                                             | 
                                                40.39
                                                
                                             | 
                                                29.25
                                                
                                             | — | — | — | 
                                                3.34
                                                
                                             | 
                                                1.94
                                                
                                             | — | 
| Equity-to-asset ratio | 
                                                0.442
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.439
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.486
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.502
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.637
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.597
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.641
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.689
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.679
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.745
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                -0.028
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                -0.106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.371
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.351
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.029
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.015
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.025
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.003
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.002
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                18.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                31.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                144.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                247.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.613
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.494
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                5.967
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                678,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,691,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,014,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                1,001,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,320,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -4,946,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -4,822,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -4,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -284,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,875,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,780,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,154,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                9,195,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,707,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,510,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,570,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                2,133
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                658
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,172
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                675
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,262
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,280
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                632
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,292
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                622
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                66
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                53
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                232
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Total shareholder return | — | — | 
                                                0.950
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.358
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.558
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.277
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.203
                                                
                                                    
                                                        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
                                                    
                                                
                                             |