Quarterly Consolidated Balance Sheet
| Concept | As at 2024-09-30 | As at 2024-03-31 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                3,073,047,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,848,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Merchandise and finished goods | 
                                                320,025,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                112,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Work in process | 
                                                310,207,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                99,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                759,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                649,791,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                19,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,126,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -1,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                6,630,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,269,475,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                4,946,739,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,058,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | 
                                                11,730,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,720,496,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -9,763,641,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,661,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Buildings and structures, net | 
                                                1,966,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,059,180,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles | 
                                                11,032,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,894,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -8,877,240,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -8,745,985,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles, net | 
                                                2,155,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,148,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                110,608,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                110,608,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets | 
                                                27,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -21,629,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -18,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets, net | 
                                                5,982,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                655,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                693,664,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                588,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                564,408,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -536,620,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -527,168,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other, net | 
                                                51,949,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Other | 
                                                12,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                60,986,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                71,614,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                1,364,539,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,397,041,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                249,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                254,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                546,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                586,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -3,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                6,372,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,526,893,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                13,002,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,796,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                162,972,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                197,564,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                34,259,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,652,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,351,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,015,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Long-term borrowings | 
                                                263,388,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                378,070,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                1,953,795,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,951,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                60,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                17,602,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,381,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                2,343,326,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,426,926,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                3,694,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,442,443,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                186,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                186,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                7,325,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,354,979,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -392,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -392,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                9,158,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,188,074,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                13,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,226,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                18,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,828,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Remeasurements of defined benefit plans | 
                                                116,543,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                127,795,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                148,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                165,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                9,307,495,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,353,925,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                13,002,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,796,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |