Hidetsugu Doumoto
Doumoto is Masatsugu's father and the founder and chairman of the Seidoukai. At the time of the story he is an old man looking to Masatsugu to take control of the clan. In his youth, he was a vicious man and a former boss of the Kawaguchi family. He had a strong friendship/rivalry with Sanada; when Sanada is announced as the next boss of the family, Doumoto withdraws and forms the Seidoukai. In the ensuing conflict, he kills Sanada and takes Sanada's two children. It is implied that later Doumoto has an inappropriate relationship with Hisako that drives her to try and take her own life. He attacks Reiji when Reiji finds out the truth.