Key Financial Data Of Group
| Concept | As at 2024-03-31 | 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 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 | 2019-10-01 to 2020-09-30 | As at 2020-09-30 | As at 2020-09-30 | 2019-10-01 to 2020-09-30 | 2018-10-01 to 2019-09-30 | As at 2019-09-30 | 2018-10-01 to 2019-09-30 | As at 2019-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||||||||
| Net sales | — | — | 
                                                3,452,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,906,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,683,566,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,283,132,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,789,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,560,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Operating revenue | — | 
                                                574,292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                288,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                636,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                744,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                912,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                885,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Ordinary profit (loss) | — | 
                                                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
                                                    
                                                
                                             | 
                                                68,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -189,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                71,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                38,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                127,119,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                43,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                11,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -429,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -310,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,154,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                127,035,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                43,968,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -428,965,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -310,355,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,879,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | 
                                                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
                                                    
                                                
                                             | — | — | 
                                                860,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                855,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,231,413,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,250,814,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                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
                                                    
                                                
                                             | — | — | 
                                                3,546,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,922,149,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,641,122,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,414,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                597.44
                                                
                                             | — | 
                                                554.27
                                                
                                             | — | — | 
                                                359.28
                                                
                                             | — | 
                                                410.32
                                                
                                             | — | — | 
                                                342.71
                                                
                                             | 
                                                374.08
                                                
                                             | — | 
                                                361.92
                                                
                                             | — | 
                                                361.20
                                                
                                             | — | — | 
                                                721.06
                                                
                                             | 
                                                716.36
                                                
                                             | — | — | 
                                                1,009.52
                                                
                                             | — | 
                                                1,025.43
                                                
                                             | 
| Basic earnings (loss) per share | — | 
                                                95.09
                                                
                                             | 
                                                94.84
                                                
                                             | — | — | — | — | — | — | 
                                                36.13
                                                
                                             | — | 
                                                16.57
                                                
                                             | 
                                                -23.29
                                                
                                             | — | — | 
                                                9.18
                                                
                                             | — | 
                                                -361.77
                                                
                                             | — | 
                                                -358.09
                                                
                                             | 
                                                -270.59
                                                
                                             | — | — | 
                                                -258.79
                                                
                                             | 
                                                37.03
                                                
                                             | — | 
                                                1.82
                                                
                                             | — | 
| Diluted earnings per share | — |  |  | — | — | — | — | — | — |  | — |  |  | — | — |  | — |  | — |  |  | — | — |  |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                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
                                                    
                                                
                                             | — | — | 
                                                0.242
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.218
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.466
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.518
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                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
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.002
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                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
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                559.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                244,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -69,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -20,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -436,227,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -6,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -233,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                22,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                108,526,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                269,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                56,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                57,867,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -20,003,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -50,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -177,646,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -831,467,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -256,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,603,287,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                496,297,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                1,183,893,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                967,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,105,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,687,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,324,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                669,105,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                37
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                173
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                174
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                24
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |