The founder of the Ushiku Domain, Shigemasa YAMAGUCHI, at first worked for Nobukatsu ODA, the second son of Nobunaga ODA, and subsequently served Ieyasu TOKUGAWA.
牛久藩の藩祖・山口重政ははじめ織田信長の次男・織田信雄に仕え、その後に徳川家康に仕えた。