In February 1470, right in the middle of the Onin War, Noriyuki OUCHI planned a rebellion against Masahiro OUCHI in Suo no kuni (Suo Prefecture, currently Yamaguchi Prefecture) who was away fighting in Kyoto at the time, getting on his side people including Takemori NAITO, Moriyasu NIHO, Nobuyori YOSHIMI and Kazukane SUFU, through Chikashige OTOMO and Katsumoto HOSOKAWA of the Eastern alliance which was attacking the family estate.
大内教幸は応仁の乱真っ只中の1470年2月、家督を奪うべく東軍側であった大友親繁や細川勝元と通じて、内藤武盛・仁保盛安、吉見信頼や周布和兼を味方に付け、京都に出陣中であった大内政弘に対し周防国で謀叛を起こした。