At the end of the 15th century, Ujichika IMAGAWA who won succession dispute with the help of his uncle Soun HOJO attempted invasion upon Totomi Province, which had failed at the time of his late father Yoshitada IMAGAWA.
15世紀末に至り、伯父北条早雲の助けで家督争いに勝利した今川氏親は、亡父今川義忠の代で頓挫していた遠江国への再侵攻を試みた。