Semi-Annual Consolidated Balance Sheet
| Concept | As at 2023-09-30 | As at 2022-12-31 | 
|---|---|---|
| Semi-annual consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,341,308,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,206,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                132,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                128,287,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -581,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                2,620,438,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,702,652,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                13,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Intangible assets | ||
| Intangible assets | 
                                                4,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,413,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                280,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                248,781,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Deferred tax assets | 
                                                36,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                252,707,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                209,122,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -8,591,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -7,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                298,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                273,994,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                2,919,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,976,646,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                6,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                333,727,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                295,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,348,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,366,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Lease liabilities | 
                                                574,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                12,738,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                138,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                109,930,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                1,487,370,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,476,717,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for retirement benefits for directors (and other officers) | 
                                                62,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                44,927,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for bonuses | 
                                                43,879,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provision for bonuses for directors (and other officers) | 
                                                3,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Share capital | 
                                                319,256,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                315,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | ||
| Capital surplus | 
                                                119,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                115,871,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                1,053,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,134,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -73,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -55,989,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                1,418,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,510,055,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                6,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -17,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                6,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -17,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                6,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                1,431,758,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,499,929,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                2,919,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,976,646,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |