Semi-Annual Consolidated Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-12-31 | 
|---|---|---|
| Semi-annual consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                5,240,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,555,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                3,875,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,561,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                5,395,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,717,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Investments and other assets | 
                                                61,436,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                61,857,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Non-current assets | 
                                                61,436,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                61,857,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                5,456,992,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,778,946,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                11,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                101,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Asset retirement obligations | 
                                                5,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                5,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                107,217,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Share capital | 
                                                4,047,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,045,977,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | ||
| Capital surplus | 
                                                4,025,098,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,023,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                -2,729,424,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,389,247,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                5,342,927,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,680,550,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                6,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                5,349,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,687,452,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                5,456,992,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,778,946,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |