Semi-Annual Consolidated Balance Sheet
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Semi-annual consolidated balance sheet | ||||||||||||||||||||||||||||||||||||||||||
| Balance sheet | ||||||||||||||||||||||||||||||||||||||||||
| Assets | ||||||||||||||||||||||||||||||||||||||||||
| Current assets | ||||||||||||||||||||||||||||||||||||||||||
| Cash and deposits | — | — | — | — | 
                                                8,573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                13,548,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | 
                                                7,586,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                7,150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Allowance for doubtful accounts | — | — | — | — | 
                                                -20,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -12,537,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | — | — | — | — | 
                                                422,461,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                387,293,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | ||||||||||||||||||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | — | 
                                                114,375,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                109,308,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Property, plant and equipment | ||||||||||||||||||||||||||||||||||||||||||
| Land | — | — | — | — | 
                                                18,876,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                18,953,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Leased assets | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Leased assets, net | — | — | — | — | 
                                                920,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Construction in progress | — | — | — | — | 
                                                10,401,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                7,457,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | ||||||||||||||||||||||||||||||||||||||||||
| Other | — | — | — | — | 
                                                195,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                208,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | — | — | — | — | 
                                                32,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                26,460,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | — | — | — | — | 
                                                376,306,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                384,917,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | ||||||||||||||||||||||||||||||||||||||||||
| Investment securities | — | — | — | — | 
                                                16,252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                18,931,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Long-term loans receivable | — | — | — | — | 
                                                4,332,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,134,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | — | — | — | — | 
                                                4,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,760,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | 
                                                1,279,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Allowance for doubtful accounts | — | — | — | — | 
                                                -160,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | — | — | 
                                                523,226,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                520,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | — | — | 
                                                945,687,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                907,978,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | ||||||||||||||||||||||||||||||||||||||||||
| Current liabilities | ||||||||||||||||||||||||||||||||||||||||||
| Short-term borrowings | — | — | — | — | 
                                                59,504,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                24,189,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Lease liabilities | — | — | — | — | 
                                                362,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Income taxes payable | — | — | — | — | 
                                                397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | 
                                                1,312,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,643,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | — | — | 
                                                320,179,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                285,532,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | ||||||||||||||||||||||||||||||||||||||||||
| Bonds payable | — | — | — | — | 
                                                25,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                25,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Long-term borrowings | — | — | — | — | 
                                                132,640,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                150,443,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Lease liabilities | — | — | — | — | 
                                                614,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                792,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Asset retirement obligations | — | — | — | — | 
                                                273,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                402,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | 
                                                2,146,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | — | — | 
                                                166,634,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                184,887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | — | — | 
                                                486,813,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                470,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Provision for bonuses | — | — | — | — | 
                                                2,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,256,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Provision for bonuses for directors (and other officers) | — | — | — | — | 
                                                122,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                88,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | ||||||||||||||||||||||||||||||||||||||||||
| Shareholders' equity | ||||||||||||||||||||||||||||||||||||||||||
| Share capital | — | — | — | — | 
                                                42,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                42,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Capital surplus | — | — | — | — | 
                                                38,704,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | — | 
                                                369,346,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                346,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Treasury shares | — | — | — | — | 
                                                -26,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -43,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Shareholders' equity | — | — | — | — | 
                                                450,682,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                427,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | ||||||||||||||||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | — | — | 
                                                8,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | — | — | — | — | 
                                                8,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | 
                                                4,536,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                288,307,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                458,874,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,661,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                74,842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -26,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,704,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                369,346,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                450,682,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,536,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                437,559,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                265,527,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                427,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                74,842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,710,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -43,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                346,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                289,619,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                380,733,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                370,919,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,536,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                74,842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,339,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                207,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | — | — | — | — | 
                                                945,687,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                907,978,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |