After forming a tripartite alliance with the Takeda clan in the Kai Province and the Hojo clan in Kanto (Zentokuji no kaimei (literally, meeting for alliance in Zentoku-ji temple)), it proceeded westward.
甲斐国の武田氏・関東の北条氏と三国同盟（善徳寺の会盟）を結ぶとさらに西進した。