Lifespan: (15xx) to (15xx)
Title: Chief of the Right Division of Outer Palace Guards
Bakufu: Muromachi, Governor of Kawachi
Father: Hatakeyama Yoshitaka
Hatakeyama Ariuji served as a bushō during the Sengoku period. Ariuji was the military governor of Kawachi Province. His common name was Shōjirō and he held the title of Chief of the Right Division of Outer Palace Guards (Deputy Governor of Kazusa). Ariuji was the sixth head of the Hatakeyama-Sōshū family. He was either the son or younger brother of Hatakeyama Yoshitaka.
In the era of Ariuji, the real power in the Hatakeyama-Sōshū family was held by a retainer named Kizawa Nagamasa, giving the appearance of a puppet administration. In 1532, after the death of Yoshitaka, Ariuji was soon backed by Nagamasa and became the head of the family. Based on written exchanges in 1537 including exemptions from special levies issued to the Kanshin Temple, Ariuji likely succeeded Yoshitaka as head of the family around that time.
The Hatakeyama-Bishū family (Masanaga branch) continued cooperation with Hatakeyama Yakurō, the head of the family, but, in 1541, after Nagamasa rebelled against Hosokawa Harumoto, Ariuji did not agree and remained in Iimori Castle. In 1542, Nagamasa was killed in action against the bakufu army at the Battle of Taiheiji. Owing to his complicity, Ariuji was also attacked at Iimori Castle by the bakufu army. Negotiations with the bakufu proceeded but ultimately failed and, in the first month of 1543, Iimori Castle fell.
Thereafter, Ariuji sought revenge through support from the Hongan Temple and others, but, in 1547, despite serving the Harumoto administration during a rebellion by Hosokawa Ujitsuna, on 5/9 of Tenbun 18 (1549), he lost in battle against forces led by Miyoshi Nagayoshi and Yusa Naganori who were allied with Ujitsuna. His later whereabouts are unknown and he was succeeded by his son, Hatakeyama Naomasa.