Nemuri Kayama ( Kayama Nemuri?), also known as the 18+ Only Hero: Midnight (18禁ヒーロー ミッドナイト Jū-hachi-kin Hīrō Middonaito?), is a Pro Hero and faculty member at U.A. High School, who teaches Modern Hero Art History. She was also the Chief Referee of the U.A. Sports Festival for the first-year students.