Hōjō Masako
Hōjō Tokimasa helped Minamoto no Yoritomo, a son-in-law, defeat the forces of the Taira to become Japan's first "shōgun". Hōjō Masako, Tokimasa's daughter, was married to Yoritomo. After the death of Yoritomo, Tokimasa became "shikken" (regent) to the child "shōgun", thus effectively transferring control of the shogunate to his clan permanently. The Minamoto and even Imperial Princes became puppets and hostages of the Hōjō.