最上氏
Mogami Yoshiaki was the first son of Mogami Yoshimori (), of the Mogami clan and succeeded his father as "daimyō" of Yamagata. When Yoshihime, who was his sister, married Date Terumune, the Mogami clan allies with the Date clan. During this time, Yoshihime wrote information about the Date clan to Yoshiaki, her and Yoshiaki's actions made the Date clan distrust the Mogami family. Yoshiaki fought against the Date clan twice in different years, in both battles Yoshihime advanced to the middle of the battlefield to create a peace treaty.