Mr. Mark teaches history at Hitsue Middle School, and he kicks off the series with a lesson on the Second Battle of Kawanakajima in 1555, breaking down the conflict between Takeda Shingen and Uesugi Kenshin. He's known for using history trading cards as teaching tools and really pushing his students to participate in class discussions. His influence on Aichi is huge—Mark's encouragement is basically what gets Aichi to take competitive Vanguard seriously in the first place, making him central to Aichi's whole character arc.
What most people don't know is that Mark also operates as Ninja Master M outside the classroom.
By the third season, he's moved up to teach at Hitsue High School and serves as the faculty advisor for the school's Vanguard Club.
Content compiled by AnimeList.moe from publicly available sources.
