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 | — | 
                                                2,337,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,775,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,650,023,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,178,153,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Depreciation | — | — | 
                                                1,621,222,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,374,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Impairment losses | — | — | 
                                                47,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in allowance for doubtful accounts | — | — | 
                                                69,587,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -24,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -121,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -115,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                50,917,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,017,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                -58,273,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -17,418,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                -259,526,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                403,189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                275,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                88,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                6,125,365,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,337,968,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                133,321,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                128,627,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -50,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -40,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes paid | — | — | 
                                                -1,294,701,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -548,175,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                4,913,073,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                878,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | — | — | 
                                                -1,150,342,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -662,130,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of property, plant and equipment | — | — | 
                                                212,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of investment securities | — | — | 
                                                -110,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of investment securities | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                95,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                21,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                35,501,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -1,864,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,643,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from financing activities | |||||||
| Proceeds from long-term borrowings | — | — | 
                                                12,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,053,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of long-term borrowings | — | — | 
                                                -214,918,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -44,116,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -507,951,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -453,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -2,412,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,416,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -480,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -794,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                1,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,683,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                2,568,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,546,844,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | 
                                                8,093,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                5,524,824,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,071,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |