Fujita advocated that Yoshiaki ASHIKAGA existed in the background of Mitsuhide pointing out that, as evidences to substantiate his view, Mitsuhide's envoy who was sent to Kagekatsu UESUGI immediately before Honnoji Incident asking for cooperation stated 'The Uesugi should cooperate' ('Kakujokogoshoshu') requesting cooperation to a person who was in higher position than Uesugi's.
藤田はこの説を裏付ける証拠として、本能寺の変の直前に光秀が上杉景勝に協力を求めて送った使者が、「御当方（上杉のこと）無二御馳走（協力）申し上げるべき」（「覚上公御書集」より）と、明らかに上杉より身分の高い人物への協力を促していることを示している。