Hōjō Tokimasa
Hōjō Tokimasa became regent for Shogun Yoriie, Yoritomo's son who disliked the Hōjō and preferred his father-in-law's family, the Hiki clan under Hiki Yoshikazu. Yoshitoki, Masako, and Tokimasa presided over a council of regents in 1200 to help Yoriie in ruling the country, but Yoriie distrusted the Hōjō, and in 1203 plotted with Yoshikazu to have Hōjō Tokimasa murdered. Yoshitoki had no idea about this, but Masako found out and told her father. Tokimasa had Yoshikazu executed in 1203. During the gore, Yoriie's son and heir, Minamoto no Ichiman, was also executed. Yoriie, out of support, abdicated in 1203, went to live in Izu, and was executed on Tokimasa's orders in 1204. Both Masako and Yoshitoki were not expecting this.