Quarterly Consolidated Statement Of Cash Flows
| Concept | 2024-04-01 to 2024-09-30 | As at 2024-09-30 | As at 2024-03-31 | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | 
                                                10,217,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                389,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                66,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -2,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -90,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -96,465,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                -82,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                290,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | 
                                                -31,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of investment securities | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,078,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -32,219,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,119,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Purchase of treasury shares | 
                                                -11,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -196,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -158,428,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -196,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -159,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                -311,628,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                134,040,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                3,443,897,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,755,526,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,553,087,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,419,047,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |