Quarterly Consolidated Statement Of Cash Flows
| Concept | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | 2022-10-01 to 2023-09-30 | 2021-10-01 to 2022-09-30 | 2021-10-01 to 2022-09-30 | As at 2022-09-30 | As at 2021-09-30 | 
|---|---|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | — | 
                                                660,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,276,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                654,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                381,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Depreciation | — | — | 
                                                322,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                369,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Impairment losses | — | — | 
                                                22,896,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                178,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -9,465,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                8,757,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,685,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in trade receivables | — | — | 
                                                142,262,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                -7,409,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                36,969,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -129,237,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -65,541,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                112,226,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                1,123,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,172,976,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                9,465,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -8,925,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -8,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes paid | — | — | 
                                                -357,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -282,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                766,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                884,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | — | — | 
                                                -423,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -471,717,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of property, plant and equipment | — | — | 
                                                688,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of investment securities | — | — | 
                                                -23,762,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -176,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of investment securities | — | — | 
                                                149,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of shares of subsidiaries resulting in change in scope of consolidation | — | — | 
                                                -206,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -46,178,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -1,974,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                418,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -743,190,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from financing activities | |||||||
| Proceeds from long-term borrowings | — | — | 
                                                485,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of long-term borrowings | — | — | 
                                                -735,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -637,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Redemption of bonds | — | — | 
                                                -62,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -57,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from issuance of shares | — | — | 
                                                2,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,324,028,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -175,106,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -76,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -425,334,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                263,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                1,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                759,028,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                403,985,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | 
                                                1,854,553,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,095,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                691,539,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |