Asuka is the most popular girl at Haramaku High School and a classmate of Tomoko Kuroki. Katou initially appears a glamorous and popular girl outside of students who know Tomoko. She has a mother from whom she seems to have inherited her looks, and an older brother who was in college when she was in middle school. Katou is widely considered to be the "Class Mom", always working to include everyone in social activities and acting as mediator anytime conflict arise inside the class.

She is curiously interested in Tomoko Kuroki, the resident NEET and they are rarely seen apart.