Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 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 | 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 | — | — | — | — | — | — | — | — | — | 
                                                4,686,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,359,273,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,279,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,583,458,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,581,739,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,886,741,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,761,697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,069,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,142,414,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,409,262,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | — | — | — | — | 
                                                84,722,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                198,242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,727,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                146,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                158,309,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                146,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                134,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                159,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -759,281,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -684,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                207,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -385,982,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                247,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                133,715,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -798,482,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,495,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,495,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,495,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,495,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | — | 
                                                23,305,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                23,305,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                23,305,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                23,305,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                23,305,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | — | 
                                                1,803,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,584,607,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,693,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,361,910,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,747,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,533,807,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,286,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,503,152,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,289,693,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,365,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | — | 
                                                8,680,147,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,757,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,987,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,936,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,053,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,590,763,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,666,803,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,081,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,032,799,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,154,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | — | 
                                                77.48
                                                
                                             | — | — | 
                                                68.08
                                                
                                             | — | — | — | — | 
                                                72.76
                                                
                                             | 
                                                58.51
                                                
                                             | — | 
                                                75.06
                                                
                                             | 
                                                65.89
                                                
                                             | — | — | — | 
                                                55.26
                                                
                                             | 
                                                64.55
                                                
                                             | 
                                                55.36
                                                
                                             | — | — | 
                                                58.62
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — |  |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — |  |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | — | — | — | — | 
                                                3.82
                                                
                                             | — | — | — | 
                                                8.90
                                                
                                             | 
                                                -16.58
                                                
                                             | 
                                                4.38
                                                
                                             | — | — | 
                                                10.65
                                                
                                             | — | — | 
                                                9.23
                                                
                                             | 
                                                5.74
                                                
                                             | 
                                                -3.77
                                                
                                             | — | — | — | 
                                                -34.33
                                                
                                             | 
                                                -36.89
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | — | — | — | — |  | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | — | 
                                                0.208
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.204
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.212
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.196
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.248
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.212
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.161
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.191
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | — | — | — | — | 
                                                0.051
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.141
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.283
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.060
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.142
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.152
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.089
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.068
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                -0.585
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.507
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | — | — | — | — | 
                                                45.03
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                19.33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                31.28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                12.86
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                14.84
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23.17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | — | — | 
                                                370,119,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                337,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                423,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                373,772,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -6,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | — | — | 
                                                -846,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -473,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -256,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -713,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -131,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | — | — | 
                                                617,910,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                220,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -288,495,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -339,461,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,372,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | 
                                                1,802,191,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,665,328,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,531,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,657,580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,320,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                78
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                231
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                232
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                148
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                150
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                238
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                253
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                154
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                278
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                170
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | — | 
                                                1.211
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.965
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.965
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.937
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.394
                                                
                                                    
                                                        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
                                                    
                                                
                                             |