Riko Tsukimi is the homeroom teacher for Tooru and Julie in Kouryou Academy. She has just graduated as a student from Kouryou then became a teacher. She knows all of Sakuya's secrets and is also an acquaintance of her. Since Tooru has a duo of the opposite gender, most of her perverted jokes are directed towards him, which causes misunderstandings around him. Rito has two personalities. The white Usa-sensei (usagi-sensei) and the black Usa-sensei. (Nickname given by the students when she reveals her true nature). The white Usa-sensei is the good girl and cheerful one who always plays innocent. The black Usa-sensei is the foul-mouthed teacher that is always angry. That is mostly the true nature of Rito who is a war freak. The only common thing between the two personalities is that they both always tease Tooru about perverted things that cause misunderstanding. (Source: Absolute Duo Wikia)