One of Ayumi's friend, Koyoi, exhibits a sibling rivalry complex. When Misao begins to spend time with Ayumi, both girls cease to walk home together with her. Additionally, they are all in the same class at school.
Since her brother likes Misaki, a popular and attractive girl, she regards her as a "Final Boss" that she must defeat. She recruits Ayumi along the way once she learns that her love, Mamoru also has a crush on Misaki. She also quotes that Misakis chest is a "truly evil power."