He accompanied his father Yoshisada even after Takauji ASHIKAGA revolted against the government of Kenmu era, and entered Kanagasaki Castle in Echizen Province in November 1336 with Yoshisada as a base to fight against the Ashikaga side in northern Japan under orders of Imperial Princes Tsuneyoshi and Takayoshi.
足利尊氏が建武政権に反逆した後も父義貞と行動をともにし、建武3年（1336年）10月、義貞と共に、足利方と戦う拠点を北国に作るため恒良親王、尊良親王を奉じて越前国金ヶ崎城に入る。