Seitarou Yagiri

Seitarou Yagiri (矢霧清太郎) is Namie and Seiji's uncle.

Charateristics
In season one, not much is shown of him, but he wears a lab coat and has silver hair.

In season two, Seitarou has brown hair, like his nephew and niece. He wears a business suit and tie as well as a monocle. His face is round and somewhat wrinkled, looking to be slightly older than middle-aged.

Dollars/Mika Harima Arc
He shows Namie Celty's head, which was found in Ireland.

Adabashi Arc
He demands that Shingen to give Celty's head to him which is revealed in a flashback. Shingen refuses. So Seitarou said that he'll mess with Shinra if Shingen didn't give him the head. Shingen did give him the head. At the end of the novel he is warned to not go near Yadogiri Jinnai.