Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2023-03-31 | 2022-10-01 to 2023-03-31 | As at 2023-03-31 | 2022-10-01 to 2023-03-31 | 2021-10-01 to 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | 2021-10-01 to 2022-09-30 | As at 2021-09-30 | 2020-10-01 to 2021-09-30 | As at 2021-09-30 | 2020-10-01 to 2021-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||||||
| Net sales | — | 
                                                3,594,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                3,452,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,906,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,683,566,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,283,132,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Operating revenue | — | — | — | — | — | — | 
                                                583,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                574,292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                288,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                636,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                744,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary profit (loss) | — | 
                                                216,028,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -25,834,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                128,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                73,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                45,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,121,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -25,895,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                38,552,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -246,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) | — | — | — | — | — | — | 
                                                -26,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                127,446,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                20,111,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -28,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -433,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | 
                                                131,792,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                201,582,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                80,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                284,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                284,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Total number of issued shares | — | — | — | — | 
                                                1,606,600
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,435,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                1,219,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                1,219,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                1,219,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
| Net assets | 
                                                1,184,279,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                907,289,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                853,697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                792,006,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                435,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                497,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                415,844,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                453,919,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                435,180,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                434,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                2,328,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,656,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,378,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,835,613,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,739,307,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,209,575,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,912,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,342,811,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,772,940,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,128,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets per share | 
                                                370.06
                                                
                                             | — | — | — | 
                                                283.51
                                                
                                             | — | — | — | — | — | 
                                                298.72
                                                
                                             | 
                                                277.13
                                                
                                             | 
                                                179.64
                                                
                                             | — | 
                                                205.16
                                                
                                             | — | — | 
                                                171.35
                                                
                                             | 
                                                187.04
                                                
                                             | — | 
                                                180.96
                                                
                                             | — | 
                                                180.60
                                                
                                             | — | 
| Dividend paid per share | — | — | — | — | — | — | 
                                                30.0
                                                
                                             | — | 
                                                15.0
                                                
                                             | — | — | — | — | — | — | 
                                                12.0
                                                
                                             |  | — | — | — | — |  | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — |  | — |  | — | — | — | — | — | — |  |  | — | — | — | — |  | — | — | 
| Basic earnings (loss) per share | — | 
                                                65.04
                                                
                                             | — | — | — | — | 
                                                -9.26
                                                
                                             | — | 
                                                47.54
                                                
                                             | 
                                                47.42
                                                
                                             | — | — | — | 
                                                18.07
                                                
                                             | — | 
                                                8.29
                                                
                                             | 
                                                -11.65
                                                
                                             | — | — | 
                                                4.59
                                                
                                             | — | 
                                                -180.88
                                                
                                             | — | 
                                                -179.04
                                                
                                             | 
| Diluted earnings per share | — |  | — | — | — | — |  | — |  |  | — | — | — |  | — |  |  | — | — |  | — |  | — |  | 
| Equity-to-asset ratio | 
                                                0.509
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.548
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.359
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.431
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.251
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.225
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.217
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.194
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.157
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.139
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Rate of return on equity | — | 
                                                0.185
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.208
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.188
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.092
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.025
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Price-earnings ratio | — | 
                                                8.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                25.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                55.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Payout ratio | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.126
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.724
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                190,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                244,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -69,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -20,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -436,227,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | 
                                                43,620,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                22,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                108,526,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                269,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                56,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | 
                                                -148,589,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -50,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -177,646,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -831,467,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -256,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                1,269,604,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,183,893,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                967,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,105,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,687,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Number of employees | 
                                                117
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Average number of temporary employees | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Total shareholder return | — | — | — | — | 
                                                1.250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.966
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.057
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.887
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.033
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Total return on share price index | — | — | — | — | 
                                                1.824
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1.853
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.311
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.184
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.275
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — |