Tsumugi is an honors type student who speaks in a docile and gentle way, but she becomes very passionate when she talks about her favorite series or cosplays. She tends to call herself and everything that she has done "plain," as she believes that among all of the students, she is the one who has the plainest appearance and personality. Despite her plain and docile attitude, certain hints suggest that she may actually be quite perverted, as she is a big stereotypical fan of anime and manga.