Consolidated Balance Sheet
| Concept | As at 2025-03-31 | As at 2024-09-30 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,973,546,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,152,744,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accounts receivable - trade | 
                                                1,510,451,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,535,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                187,219,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                172,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -8,699,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -5,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                3,662,518,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,855,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                750,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                552,547,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                310,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                244,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -13,774,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | ||
| Property, plant and equipment | 
                                                407,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                269,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Intangible assets | 
                                                32,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,463,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Assets | 
                                                4,413,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,407,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Short-term borrowings | 
                                                918,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                40,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,442,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accrued expenses | 
                                                986,913,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,055,205,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                235,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                175,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                2,354,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,252,803,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Deferred tax liabilities | 
                                                13,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                146,121,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                150,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                132,724,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                136,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                2,500,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,402,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Shareholders' equity | 
                                                1,866,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,969,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                157,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                157,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                1,861,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,964,622,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -152,306,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -152,306,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                45,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,916,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                1,912,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,004,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                4,413,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,407,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity |