According to a legend, when Yoshimoto IMAGAWA was defeated by Nobunaga ODA at the Battle of Okehazama in 1560, Ieyasu TOKUGAWA (those days, Motoyasu MATSUDAIRA) who had been following the Imagawa clan tried to execute seppuku (ritual suicide) in Daiju-ji Temple under Okazaki-jo Castle.
永禄3年（1560年）、桶狭間の戦いで今川義元が織田信長によって討たれると、、それまで今川氏に従属していた徳川家康（当時は松平元康）は、岡崎城下の大樹寺で切腹を図ろうとしたと伝わる。