Originally from Musashi Province, Hiki Yoshikazu rose to prominence in the shogunal government as a result of being adopted by Minamoto no Yoritomo's wet nurse.

Seriously ill, Yoriie proposed to name both his younger brother Sanetomo, and his young son (Hiki's grandson) Minamoto no Ichiman to succeed him; the two would split power, governing separate parts of the country.

He therefore suggested to Yoriie, who would be assassinated shortly afterwards by a separate faction (the Hōjō clan), that they arrange to have Sanetomo killed.

Hōjō Masako, Yoriie's mother and wife of the first shōgun Yoritomo, overheard this conversation.

In their schemes to dominate the regency and control the shogunate as a puppet government under their clan, Hōjō warriors assassinated Hiki Yoshikazu, and then attacked the palace of young Ichiman, setting a fire and killing both the young heir and a great number of members of the extended Hiki family.