Mary Holmes is a supporting character in the London chapter of D.C.III ~Da Capo III~, which takes place in the 1950s past timeline of the story. She is a student at the underground magical school known as the Weather Vane. Mary comes from a distinguished family of detectives, which influences her energetic and competitive personality. She is extremely lively, often described as hot-blooded, and enjoys challenging others in various activities, from sports to student council elections. She is almost always accompanied by Edward Watson, her childhood friend, with whom she forms a comedic duo. Their dynamic is a key aspect of her interactions, as they frequently banter and get into mischief together. Mary has a tendency to jump at every chance to compete, and this drive sometimes leads her into minor conflicts, such as a near scuffle with a character named Mikoto in a game center on Hatsunejima. In the overarching narrative, Mary serves as a minor figure within the flashback sequences, adding color and comic relief to the group of students who later reincarnate in the present-day storyline. While she is not one of the main heroines, her presence helps flesh out the world of the 1950s London magical academy. Physically, she has long pink hair, green or cyan eyes, stands 151 centimeters tall, and weighs 44 kilograms. Her notable abilities are not explicitly detailed in available sources, but her detective family background implies keen observational skills and a knack for investigation. Her motivations center on proving herself through competition and supporting her friends, especially Edward. Mary undergoes little personal development within the limited screen time she receives, remaining a consistently high-spirited and competitive presence.