Lifespan: Bunmei era (around 1470) to eighth month of Meiō 7 (1498)
Clan: Ashikaga (Horigoe kubō)
Bakufu: Muromachi bakufu
Father: Ashikaga Masatomo
Siblings: Chachamaru, Yoshizumi, Jundōji, Oda Masaharu (?)
Ashikaga Chachamaru served as a bushō during the latter part of the Muromachi period. He was the son of Ashikaga Masatomo, the first Horigoe kubō. Following the death of Masatomo in 1491, Chachamaru initiated and prevailed in a succession struggle against his half-brother of a different mother, Ashikaga Jundōji. Later, however, he was attacked by Ise Sōzui (later known as Hōjō Sōun), and following a series of battles, killed himself, ending the governance of the Horigoe kubō. Chachamaru was a name from his youth, but he died prior to holding a coming-of-age ceremony, so was not known under an adult name. Ashikaga Yoshizumi, the eleventh shōgun, was also a half-brother of Chachamaru.
Despite Chachamaru’s position as the eldest son, Masatomo ordered him to be incarcerated in a dungeon owing to his delinquent behavior, and designated his younger brother, Jundōji, as Masatomo’s successor. Under one theory, Jundōji’s birth mother, Enman-in, committed slander against Chachamaru to Masatomo. Uesugi Masanori (a senior official under Masatomo) opposed the removal of Chachamaru from the line of succession, but Masatomo disregarded his opinion, compelling Masanori to take his own life. Following the death of Masatomo in the fourth month of 1491, Chachamaru continued to be mistreated by Enman-in. In the summer, he killed the guard and broke out of prison, whereupon he murdered both Jundōji (the designated successor to Masatomo as the second Horigoe kubō) and Enman-in, thereby becoming the next Horigoe kubō.
Nevertheless, Chachamaru believed the slander he heard from a disloyal subordinate, after which he proceeded to slay several senior retainers, including Sotoyama Buzen-no-kami (the head elder and lord of Nirayama Castle) and Akiyama Shinkurō. This caused him to lose the support of other longtime retainers and escalated into an internal conflict in Izu. In the tenth month of 1493, Ise Sōzui (later Hōjō Sōun) from Kōkokuji Castle intervened in the struggle. Suzuki Shigemune, Matsushita Sanrō (the Lieutenant of the Outer Palace Guards of the Right Division), the Ōmi Group of Three (Ōmi no sanninshū) and others invaded Izu upon request of influential local families, while Chachamaru was regarded as a traitor for killing Enman-in, the mother of Ashikaga Yoshizumi, the new shōgun. Having lost its standing, the Horigoe kubō quickly dissolved. In 1495, Sōzui banished Chachamaru from Izu, after which Chachamaru sought to recover Izu with the support of the Yamauchi-Uesugi and the Takeda clans. Chachamaru killed himself in the eighth month of 1498 after he was apprehended by Sōzui in Kai Province.