Sae Kisaragi

Yuuto, Rinko, and Himari's female school teacher. A smoker and perverted, she seems to always catch Yuuto in an erotic act with a girl. She is actually passively supportive of whatever erotic acts the students do as long as they do it outside of class time. Also in chapter 8 it is implied she may have powers or a youkai as well. Rinko sometimes calls her "Sae-chan" which she detests.