In 1457, when Norihiro OUCHI, a Sengoku daimyo (Japanese territorial lord in the Sengoku period) in Suo Province, attacked the Aki-Takeda clan in terms of his relationship with the family of Itsukushima-jinja Shrine priest, Yukitsune supported the Aki-Takeda clan by the order of Katsumoto HOSOKAWA, Kanrei, shogunal deputy, together with the Mori clan and other Aki kokujins to beat back the Ouchi troops (the Yamamoto Battle).
1457年（長禄元年）、周防国の戦国大名・大内教弘が厳島神主家との関係で安芸武田氏を攻めた際には、管領・細川勝元の命を受け、毛利氏ら安芸国人とともに安芸武田氏を支援して大内軍を撃退した（山本合戦）。