Semi-Annual Consolidated Balance Sheet
| Concept | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2024-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2023-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | As at 2022-04-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Semi-annual consolidated balance sheet | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Balance sheet | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cash and deposits | — | — | — | 
                                                5,235,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,197,074,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,916,630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,377,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Securities | — | — | — | 
                                                3,199,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,199,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                9,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,678,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | — | — | — | 
                                                11,883,435,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,848,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                10,915,948,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,374,561,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | 
                                                3,006,033,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,006,033,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,427,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,424,867,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Property, plant and equipment | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Buildings and structures | — | — | — | 
                                                2,507,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,508,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | 
                                                -1,729,523,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -1,672,007,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Buildings and structures, net | — | — | — | 
                                                777,718,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                836,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Machinery, equipment and vehicles | — | — | — | 
                                                7,326,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                7,084,393,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | 
                                                -6,063,169,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -6,046,424,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Machinery, equipment and vehicles, net | — | — | — | 
                                                1,263,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,037,968,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Land | — | — | — | 
                                                942,686,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                942,686,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                501,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                501,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Construction in progress | — | — | — | 
                                                1,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                30,757,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                28,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                506,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                499,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | 
                                                -486,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -479,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other, net | — | — | — | 
                                                20,524,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                20,207,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intangible assets | — | — | — | 
                                                5,636,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                8,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,314,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | — | — | — | 
                                                3,008,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,763,261,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,504,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,331,555,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment securities | — | — | — | 
                                                2,550,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,550,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,877,946,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,877,946,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Long-term loans receivable | — | — | — | 
                                                100,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                100,463,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                100,463,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | — | — | — | 
                                                3,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,819,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                96,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                83,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                81,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                94,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | — | 
                                                6,019,913,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,774,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,939,831,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,764,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | — | 
                                                17,903,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,623,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                15,855,780,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                17,139,298,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Income taxes payable | — | — | — | 
                                                192,942,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                184,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                138,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                142,722,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                96,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                58,130,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                125,727,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | — | 
                                                1,411,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,402,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,935,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,967,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Long-term borrowings | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retirement benefit liability | — | — | — | 
                                                321,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                284,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                994,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                994,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | — | 
                                                946,093,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                909,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                678,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                714,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | — | 
                                                2,357,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,312,338,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,614,168,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,682,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Provision for retirement benefits for directors (and other officers) | — | — | — | 
                                                307,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                307,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                300,532,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                300,532,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Provision for bonuses | — | — | — | 
                                                198,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                192,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                225,835,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                231,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax liabilities | — | — | — | 
                                                316,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                279,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                89,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                125,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholders' equity | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Share capital | — | — | — | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Capital surplus | — | — | — | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | 
                                                13,318,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,084,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                11,453,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,984,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Treasury shares | — | — | — | 
                                                -10,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -10,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -9,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -9,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Shareholders' equity | — | — | — | 
                                                14,365,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,130,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                12,499,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,030,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | — | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                741,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                741,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Foreign currency translation adjustment | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                683,939,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | — | — | — | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                741,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,425,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | 
                                                13,318,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -10,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,546,228,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,311,353,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,365,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,136,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,130,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -10,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,084,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,181,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,241,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,456,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                741,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,030,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,499,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,425,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                741,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,453,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,984,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                683,939,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,305,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                669,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,421,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,074,688,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                589,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,421,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,259,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                589,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,027,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,358,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,574,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                464,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,722,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,768,930,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,334,289,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | — | — | — | 
                                                17,903,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,623,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                15,855,780,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                17,139,298,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |