Mogami Yoshiaki is the leader of the Mogami clan that rules Dewa Province. He is often known as "the Noble Fox of Dewa." He thinks of himself as a great and smart nobleman. While he is Masamune's maternal uncle, the two of them rarely hint at it, though Yoshiaki refers to him as "Masamune-kun."

(Source: Sengoku Basara Wikia, edited)