Mei Kinosaki is a major supporting character in Marriage Toxin, a manga series about assassins and marriage. She is a skilled con artist and marriage expert who helps guide the protagonist, Gero, in matters of romance and social interaction. Mei is intelligent, resourceful, and often acts as a practical advisor, using her experience to help others navigate difficult personal situations. Her role in the series is both comedic and strategic, as she supports the main cast while adding insight into relationships and human behavior.