Quarterly Consolidated Balance Sheet
| Concept | As at 2023-12-31 | As at 2023-03-31 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                3,951,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,230,689,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Merchandise and finished goods | 
                                                124,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                160,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Work in process | 
                                                189,168,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                78,414,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                637,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                530,742,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                25,965,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -1,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                7,050,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,140,537,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                4,585,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,609,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | 
                                                11,655,351,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,506,072,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -9,625,347,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,542,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Buildings and structures, net | 
                                                2,030,003,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,963,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles | 
                                                10,853,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,700,507,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -8,688,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -8,473,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles, net | 
                                                2,164,653,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,227,226,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                110,608,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                110,608,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets | 
                                                27,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -17,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -13,346,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets, net | 
                                                10,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                238,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                268,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                558,916,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                544,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -527,222,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -519,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other, net | 
                                                31,693,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,773,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Other | 
                                                10,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,628,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                77,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                94,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                1,451,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,510,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                245,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                228,931,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                645,630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                742,479,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -3,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                6,115,055,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,214,364,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                13,165,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,354,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                112,552,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,643,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                115,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,935,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,448,718,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,453,301,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Long-term borrowings | 
                                                482,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                607,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                2,046,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,044,366,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                59,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                57,719,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                6,836,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                2,623,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,721,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                4,071,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,174,658,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                186,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                114,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                7,097,107,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,194,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -392,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -320,622,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                8,930,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,027,624,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                19,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,465,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                13,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Remeasurements of defined benefit plans | 
                                                130,354,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                130,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                163,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                152,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                9,093,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,180,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                13,165,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,354,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |