Chachamaru was the son of Ashikaga Masatomo and resided at Horigoe castle in Izu province. His mother was Masatomo's first wife and Masatomo ordered Chachamaru to a temple, intending the family leadership to go to a younger son (Jundôji), whom he had sired through a second wife. When his father died, Chachamaru escaped the monastery, killed his half-brother and step-mother, and assumed control of Izu. He next put to death two retainers, Toyama Buzen no kami and Akiyama Kurando, who had opposed his rise to power. Ise Shinkûro (Hôjô Soûn), a nominal vassal of the Imagawa at the time, attacked from Suruga province after establishing that he would be welcomed by Izu's samurai. Horigoe was besieged in 1493 and Chachamaru surrendered. Ise banished Chachamaru, who found shelter in Kai with Takeda Nobutsuna. The Takeda evidently planned to assist Chachamaru in retaking Izu but this scheme was cut short when the Hôjô invaded Kai in 1498 and forced him to commit suicide. Some older sources give 1491 as the year Chachamaru was driven from Izu.