Nemuri Kayama

Nemuri Kayama (香山睡), also known as 18+ only Hero Midnight (18禁ヒーロー ミッドナイト), is a Pro Hero and staff at Yuuei. She was the Chief Referee of the Sports Festival for Year 1.

Appearance
Midnight is a very beautiful woman with long, spiky hair.

Midnight's hero costume is very similar to one of a dominatrix. She has masked eyes, a handcuff on each wrist, a utility belt around her hips, and leather high heels with transparent stockings. She is often seen carrying a bullwhip. The most unique part of the costume is her "shirt", which has a leather-like tie that is connected to the shirt that covers only below her breasts, leaving most of above her torso and arms exposed, but without leaving any of her privates exposed as she wears ultra sheer tights as a top.

Personality
Midnight has a very flirty personality, but she also has the tendency to make angry outbursts, such as when someone else interrupts her, doesn't let her finish what she's about to explain and when someone mentions her age. She seems to act on mere whims sometimes, as seen when she accepts Mashirao and Shouda's request to resign from the tournament event just because she liked their reasoning. Midnight has shown to be sadistic, as she enjoyed seeing Minoru run away in fear.

Unforeseen Simulation Joint Arc
Midnight appeared along with the other Pro heroes when Class 1-A was attacked by the Villain Alliance.

Sports Festival Arc
At the beginning, she tells everyone to play fair during the Sports Festival. The students question her "+18 only" tagline, and ask whether it is fine due to them being in high school. She yells at them and tells them to be silent. She then calls Katsuki Bakugou, the player representative for the Freshmen, up to the stage. Midnight is then seen explaining the rules of the Human Cavalry Battle and suggested to go for the one that took first place.

Midnight is seen again announcing that they will be doing drawings to determine the pairings for the tournament event and says that before the tournament begins, recreational events will take place first. She then says that the sixteen participants in the tournament event do not have to partake in the recreational events and can abstain from the events if they wish and there is no problem if they want to rest and save their energy. After Mashirao and Shouda request to resign from the tournament event, Midnight, liking their reasonings, accepts their resignations. She then says that the open slots will be filled in by the team that placed fifth: Team Kendou, but Team Kendou decides to give the opportunity to Team Tetsutetsu. Midnight then announces that Tetsutetsu and Ibara will be replacing Mashirao and Shouda. Midnight then shows the pairings for the tournament event.

During the match between Izuku and Shouto, Cementoss contacts her and asks her if he can stop the match, saying that Izuku's serious injuries would prevent him from being able to fight in the next match even if he wins, causing Midnight to think about it and eventually decided to continue the match.

After Shouto is knocked out of bounds and Katsuki angrily grabs him, Midnight knocks Katsuki out with her aroma to stop him from doing anything to Shouto.

Field Training Arc
At the request of Shouta, Midnight comes to Class 1-A's classroom to evaluate their Hero names.

End of Term Test Arc
On the day of Class 1-A's test exercise, Midnight is one of the teachers that Class 1-A will face in their end of term test exercise. Midnight will face Hanta and Minoru in their test exercise.

Minoru, Hanta, and Midnight arrive in an uninhabited city where Class 1-A's test exercise will take place. In the city, Midnight explains the 30-minute test; Minoru and Hanta must either handcuff her or one of them must escape the battlefield within 30 minutes in order to win and pass the test. The test begins. Midnight uses her Quirk to put Hanta to sleep. Midnight is sitting at the escape gate with a sleeping Hanta on her lap, much to Minoru's jealousy. Suddenly, Minoru is whipped by Midnight who has decided to chase after Minoru after she got excited from seeing Minoru's fear. Minoru tries speaking, but stops when he realizes that the moment he opens his mouth, he will become susceptible to Midnight's sleeping gas. Midnight criticizes Minoru for running away. However, Minoru tells Midnight that his cowardice and his lack of courage was all part of his plan to lure Midnight away from the escape gate and Hanta, all in the name of becoming a cool Hero. Minoru charges at Midnight with Hanta's tape wrapped around his mouth to prevent him from inhaling Midnight's sleeping gas. As Midnight whips at him, Minoru uses his move Grape Rush (which involves throwing his sticky substance from his head at the opponent while running towards them). Minoru's move hits Midnight's whip and hand, causing Midnight to become attached to her whip and stuck in place, allowing Minoru to run past her. Midnight is impressed with Minoru's strategy. Minoru takes off the tape, grabs Hanta and drags him out of the escape gate with him, allowing them to pass the practical test.

Quirk and Abilities
Somnambulist: Midnight's Quirk allows her to put targets to sleep by exuding a sleep inducing aroma from her body, as shown by her need to tear her own bodysuit around her left arm in preparation to activate it to stop Katsuki. The sleep inducing aroma works better on males than females.

Equipment and Weapons

 * High Density Weights (Combat Exam Arc) - Midnight and the rest of the teachers used these bracelets to give themselves a handicap while they fought their students.

End of Term Test Arc

 * Minoru Mineta & Hanta Sero vs. Midnight: Lose

Trivia

 * Midnight's name contains the kanji for fragance (香), mountain (山), and sleep (睡).
 * Midnight likes youth and excitement.
 * Midnight was originally planned to be Class 1-A's homeroom teacher.