Shareholdings
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Shareholdings | ||||||||||
| Reporting company | ||||||||||
| Details of specified investment shares held for purposes other than pure investment | ||||||||||
| Issue | 
                                                ZETA株式会社
                                                
                                             | 
                                                株式会社gumi
                                                
                                             | 
                                                ヒロセ通商株式会社
                                                
                                             | 
                                                株式会社デジタルプラス
                                                
                                             | 
                                                株式会社ココペリ
                                                
                                             | — | — | — | — | — | 
| Number of shares | 
                                                16,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                100,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                45,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                1,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                62,100
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                62,100
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                1,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                45,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                4,100
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                100,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Carrying amount | 
                                                7,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                40,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                181,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,306,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,679,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                540,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                135,473,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,338,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                44,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Purpose of shareholding, overview of business alliance, quantitative effects of shareholding and reason for increase in number of shares | 
                                                (保有目的)企業間取引の強化
(定量的な保有効果)(注)
(株式数が増加した理由)株式分割
                                                
                                             | 
                                                (保有目的)企業間取引の強化
(定量的な保有効果)(注)
                                                
                                             | 
                                                (保有目的)企業間取引の強化
(定量的な保有効果)(注)
                                                
                                             | 
                                                (保有目的)企業間取引の強化
(定量的な保有効果)(注)
                                                
                                             | 
                                                (保有目的)企業間取引の強化
(定量的な保有効果)(注)
                                                
                                             | — | — | — | — | — | 
| Whether issuer of aforementioned shares holds reporting company's shares | 
                                                無
                                                
                                             | 
                                                無
                                                
                                             | 
                                                無
                                                
                                             | 
                                                無
                                                
                                             | 
                                                無
                                                
                                             | — | — | — | — | — |