Anjou Mamoru is a third-year student at Tokyo Metropolitan Harumi High School. He possesses teal shoulder-length hair and orange eyes, typically wearing the school uniform: a blue suit jacket with white and dark blue trim, a red tie, a white dress shirt, and black slacks. Mamoru is teammates with two world-class fighters and is considered to be at a comparable skill level despite lacking competitive achievements. He demonstrates extreme passion for cardfighting during matches.

His involvement includes participating in the Vanguard Koshien tournament, where Harumi High advances to the semifinals against Fukuhara High School. Prior to the tournament, Mamoru challenges Toshiki Kai to a cardfight while possessing a new Overlord card, prompting Kai to recall his initial encounter with the card. As a prominent figure at the Dragon Empire branch, Mamoru organizes festivals and engages in simultaneous cardfights against multiple opponents. His leadership role includes delegating event responsibilities to his sister, Tokoha Anjou. No additional background story, development, or appearances in other media beyond the referenced events are documented.