On August 12, 1437 when the shogunate was trying to subdue the surviving retainers of the Southern Court, Yoshiaki, who was at odds with his older brother Yoshinori ran away, so the leaders of the shogunate suspected the involvement of not only Yoshiaki of Gonancho (Second Southern Court) but also Mochiuji ASHIKAGA, Kamakura Kubo (Governor-general of the Kanto region) who was in conflict with Norizane UESUGI, Kanto Kanrei (a shogunal deputy for the Kanto region), because Daikaku-ji Temple (from where Yoshiaki ran away) was associated with the Southern Court and also imperial princes of the Southern Court, Tamagawa no miya and Goshoin no miya ran away, too.
長引く南朝遺臣の討伐に加え同年7月11日(旧暦)（8月12日）、義教と不仲であった弟の義昭の出奔をみた幕府首脳は、大覚寺が南朝ゆかりであること、玉川宮、護聖院宮らの南朝皇族も共に逃亡したことなどから、後南朝・義昭に加え、当時幕府派の関東管領上杉憲実と対立していた鎌倉公方足利持氏の連携を疑った。