The Jō were warriors, allies of the Taira clan, in Echigo Province (present-day Niigata Prefecture). They were defeated in the Genpei Wars, and lost most of their power. In 1201, together with her nephew , she raised an army in response to Sukemoto's attempt (the Kennin Uprising) to overthrow the Kamakura Shogunate. Hangaku and Sukenaga took a defensive position at a fort at Tossakayama under attack from . Hangaku commanded 3,000 soldiers to defend against an army of 10,000 soldiers loyal to the Hōjō clan.