Key Financial Data Of Group
| Concept | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||
| Net sales | — | — | 
                                                11,548,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,076,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,083,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,967,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,161,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,565,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,919,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,771,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                -934,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -892,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                331,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                125,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,720,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,051,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -729,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                -1,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -740,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,016,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,329,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                -969,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                639,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -881,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,022,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                16,852,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                18,319,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,164,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,948,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                18,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,826,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,950,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                17,748,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                19,260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                18,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                21,394,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,087,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,485,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,145,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,571,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,359,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                19,870,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                1,079.45
                                                
                                             | — | — | 
                                                1,005.35
                                                
                                             | — | — | — | 
                                                1,156.86
                                                
                                             | 
                                                1,083.96
                                                
                                             | — | 
                                                1,070.26
                                                
                                             | 
                                                1,124.45
                                                
                                             | — | — | — | 
                                                1,188.11
                                                
                                             | 
                                                1,125.76
                                                
                                             | 
                                                1,133.53
                                                
                                             | — | — | 
                                                1,120.79
                                                
                                             | 
| Basic earnings (loss) per share | — | — | 
                                                -64.51
                                                
                                             | — | — | 
                                                -61.01
                                                
                                             | 
                                                22.19
                                                
                                             | 
                                                37.01
                                                
                                             | — | — | 
                                                -45.72
                                                
                                             | — | — | 
                                                -46.75
                                                
                                             | 
                                                16.76
                                                
                                             | 
                                                64.18
                                                
                                             | — | — | — | 
                                                -95.22
                                                
                                             | 
                                                -83.97
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.875
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.871
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.856
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.854
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.874
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.869
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.867
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.882
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.893
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                -0.058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.021
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.040
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.015
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.055
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                -0.081
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.074
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                26.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -1,804,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,507,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -733,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,004,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,044,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -2,680,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,085,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -639,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -509,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -160,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -193,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -225,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -219,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                7,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                12,687,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,223,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                13,235,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,095,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                205
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                223
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                205
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                227
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                204
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                213
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                244
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                287
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                258
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                266
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                59
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                70
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                69
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |