However, after Yoshimoto IMAGAWA was killed in the Battle of Okehazama, he became independent, taking the opportunity of the confusion in the Imagawa clan, and expanded his territory as a sworn friend of Nobunaga ODA (in fact a guest general).
しかしながら、桶狭間の戦いにおいて今川義元が討たれた後、今川氏の混乱に乗じて独立し、織田信長の盟友（事実上は客将）として版図を広げていく事となる。