Hes the other twins of Ran. He loved Ran and he believe that Ran wouldnt be happy if hes not with him. When he know that Ran is happy with others person A get angry and he try to kill Gingetsu He killed B before because B and Ran get to close in order to take Ran back to him. But then after he know that Ran wouldnt go back with him even with Gingetsu death. He leave Ran with Rans promise that he will not love anyone else more that A. Source: Happiness