Ichijou possesses incredible strength despite her frail and feminine appearance and is a member of the amateur wrestling club. Her power astounds even her strongest male classmates, as she can effortlessly carry a piano without showing any signs of strain, while others like Harima and Hanai struggle with objects of similar size. It seems she has difficulty controlling her strength, which is evident when she nearly suffocates Tenma by covering her mouth to prevent her from revealing secrets. Lala Gonzalez is her only rival in terms of strength but has never managed to defeat her; Ichijou defeated Lala using her ultimate move, the "Frankensteiner." Despite this rivalry, Ichijou remains polite towards Lala, and they eventually become friends.
Despite her immense strength, Ichijou has a gentle nature and is one of the more timid girls in class 2-C. She harbors feelings for Imadori but becomes embarrassed whenever it's hinted at. Initially, Imadori avoids her due to her small stature (though it's later revealed she has large breasts) and fears her strength. Ichijou is also a talented singer, and her singing is featured in episodes 2 and 6 of School Rumble - Second Term.
When Imadori encountered her practicing wrestling and asked why she liked it, Ichijou admitted that she didn't actually want to do wrestling. Later, when Imadori, Harima, and Hanai worked for a moving company, they discovered Ichijou was also working there and witnessed her extraordinary strength. At the end of their shift, Imadori accidentally mentioned he could take Karen out on a date with his earnings, to which Ichijou agreed, even though Imadori didn't mean it seriously.
Ichijou-douri is the northernmost of Kyoto's numbered east-west avenues, extending eastward to the Kyoto University campus and the grounds of Yoshida Shrine.
