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 | 
                                                1,286,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,416,013,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                123,003,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                136,403,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                2,422,838,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,710,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                10,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,547,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Intangible assets | ||
| Intangible assets | 
                                                3,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                297,744,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                287,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Deferred tax assets | 
                                                48,339,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                58,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                256,518,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                236,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -7,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -7,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                312,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                303,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                2,734,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,013,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                6,802,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                46,987,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                306,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                340,479,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,157,546,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,417,267,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Lease liabilities | 
                                                231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                403,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                12,791,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,764,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                159,851,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                144,550,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                1,317,398,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,561,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for retirement benefits for directors (and other officers) | 
                                                71,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,041,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for bonuses | 
                                                12,577,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for bonuses for directors (and other officers) | 
                                                1,248,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Share capital | 
                                                328,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                319,256,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | ||
| Capital surplus | 
                                                128,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                119,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                1,031,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,084,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -73,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -73,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                1,413,679,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,450,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                3,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,476,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                3,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,476,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                1,417,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,451,788,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                2,734,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,013,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |