Mark Whiting

A main character in Cardfight!! Vanguard: Shinemon, in which he is in his third year at high school. He initially appears as a minor character in the Cardfight!! Vanguard (V Series Anime) as a history teacher at Hitsue Middle School.

Mark is not originally from Japan, but is infatuated with the country's history and culture. He moved to Japan as a child for unknown reasons, and uses his love of Japan in his profession as a history teacher. His eccentricity and quirkiness is apparent when he teaches, and he uses a Japanese history-based trading card game to teach his lessons.

He is best friends with Shinemon Nitta, and uses his "18 years of history as a ninja" to help his friends. He is apparently a maniac for the Sengoku period of Japan. He has a ninja costume which he uses for cosplay purposes, and even has smoke bombs. While wearing his cosplay outfit, he becomes "Ninja Master", and talks in an old fashioned way, ending his sentences with "Degozaru" ("verily" in the English dub and Japanese sub).

(Source: Cardfight!! Vanguard Wiki)