Illya is the main protagonist of the show. She lives with her brother Shiro and is looked after by her maids Leysritt and Sella when her parents Kiritsugu and Irisviel are away. She is a fan of magical girl anime, and daydreams about becoming one. When she encounters a magic wand named "Magical Ruby", Illya is tricked into signing a contract and becoming a magical girl. As a magical girl, she must search for the seven "Class Cards", which contain the souls of heroic spirits.