Koharu is a member of the Supplemental Lessons Club of Trinity Integrated Academy. Originally a member of the Justice Actualization Committee, she was forcefully transferred to the Supplemental Lessons Club due to her falling grades and being made to repeat a year. While she may consider herself elite, she is actually rather stupid, so much so in fact that she is completely unable to keep up with her lessons. She has a secret hobby(?) of collecting lewd magazines, and experiences delusions about the most trivial things in everyday life, often to her own embarrassment.