Consolidated Statement Of Cash Flows
| Concept | As at 2023-09-30 | 2023-04-01 to 2023-09-30 | As at 2023-03-31 | As at 2022-09-30 | 2022-04-01 to 2022-09-30 | As at 2022-03-31 | 
|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | — | 
                                                -209,102,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                123,053,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | — | 
                                                3,916,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,412,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | — | 
                                                -113,379,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -49,452,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | — | 
                                                -12,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -12,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                -330,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                62,154,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | — | 
                                                -56,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -50,861,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of investment securities | — | 
                                                -11,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,198,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -86,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -70,893,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                -1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -834,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | ||||||
| Proceeds from long-term borrowings | — | 
                                                90,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                720,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Repayments of long-term borrowings | — | 
                                                -238,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -813,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                644,587,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,087,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                -14,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -12,846,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                226,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,651,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                722,065,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                495,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                424,965,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                426,617,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |