Quarterly Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-12-31 | 
|---|---|---|
| Quarterly balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                843,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                878,861,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Inventories | 
                                                4,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,957,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                67,386,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                68,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -2,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                1,079,162,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,114,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                157,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                162,030,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Other | — | — | 
| Other, net | 
                                                41,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                43,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Investments and other assets | ||
| Allowance for doubtful accounts | 
                                                -3,098,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,828,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                246,596,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                241,122,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                1,325,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,356,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes and accounts payable - trade | 
                                                40,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                450,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                9,663,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                53,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                87,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                700,264,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                715,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Long-term borrowings | 
                                                131,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                145,480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                40,189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                7,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,689,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                223,155,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                241,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                923,419,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                957,677,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                514,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                514,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                399,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                399,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                -438,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -445,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -71,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -71,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                404,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                397,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                -189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                -3,598,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                402,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                398,404,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                1,325,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,356,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |