Quarterly Consolidated Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-12-31 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                47,501,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                65,240,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                1,288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                6,848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,429,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                86,240,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                106,913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                130,679,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                130,108,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                80,597,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                80,940,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                25,293,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,909,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets | — | — | 
| Leased assets, net | 
                                                262,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                304,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                961,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                838,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Goodwill | 
                                                346,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                435,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                10,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,175,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                61,531,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,196,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                8,056,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,056,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term loans receivable | 
                                                9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                7,429,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,762,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                3,556,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,456,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -1,214,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,216,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                203,159,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                204,480,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                289,399,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                311,393,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                4,076,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,630,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                246,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,797,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,838,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                53,803,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,024,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Retirement benefit liability | 
                                                1,308,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                4,973,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,987,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                204,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                204,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                7,781,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                61,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                84,720,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                24,113,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,113,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                42,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                165,706,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                164,558,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                231,941,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                230,794,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Revaluation reserve for land | 
                                                -4,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Remeasurements of defined benefit plans | 
                                                75,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                81,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                -4,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,120,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                227,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                226,673,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                289,399,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                311,393,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |