Nemuri Kayama/Synopsis

History
Nemuri was a student of the U.A. At one point, he participated in the Hero Work-Studies at the Purple Revolution Agency, being sidekick the His Purple Highness. During her third year, she began a friendship with the second year students Shota Aizawa, Hizashi Yamada and Oboro Shirakumo.

It all started when, on her way home from her work-study, she went to school to do some paperwork, stopped by on one the rooftops because it's one of her favorite spots. Once there, she found the three students eating his lunch there, and she warned them that the roofs are off-limits to students, but when it seemed that she was going to admonish them, she actually praised them for their rebellious attitude.

The boys were surprised to find her there, and Shota asked her about her hero costume, because it was too revealing, to the point she was almost naked. Although she known her costume would be scorned and questioned, she told it's bold yet practical, to support both her Quirk and moves, and she didn't feel ashamed for wearing it. in fact, she was convinced that she would change the opinion of the Japanese in one year's time. Little does she know that soon, her costume would lead the government to put forward the "Hero Costume Skin Exposure Limitation Act."

Vigilante - My Hero Academia: Illegals
After a meeting with multiple Pro Heroes and the Police Force to discuss the unwilling civilians injected with Trigger, Midnight approached Eraser Head asking about where Present Mic was because he was supposed to be at the meeting. He explained that Present Mic had a cold and could not make it. Midnight scolded Eraser Head on his attire. In response, he teased her saying she should become a teacher or something if she likes counseling others so much. Much to his chagrin, she told him that was exactly what she planned on doing. Continuing on she revealed that principal Nezu personally requested her and that she would start next year at U.A. She detailed in constant innuendos her beliefs on teaching. Aizawa disagreed with her methods and as she began a rebuttal, a Suicide Bomber attacked the police station. Endeavor still fuming over what had just transpired decided he was going to incinerate the villain.

However, the villain's Quirk would most likely have a volatile reaction to Endeavor's Hellflame. Midnight called Eraser Head to help resolve the problem before it got explosive. Eraser Head wrapped up the villain and threw him into Midnight's open embrace. Suicide Bomb then landed face-first in her breasts no longer angry and passed out due to her quirk. The Midnight Boys came bursting in asking if Midnight was unharmed. She told them to hand the villain over to police custody. She told the bomber that if he acted up again, she would personally bring him to her agency and dole out punishment. Midnight returned to her conversation with Eraser Head telling him he should also become a teacher because a wide variety of opinions and teaching styles is required to educate the youth. He asked if she was joking saying if he became a teacher, it would be the epitome of irrational. The next day he was told Midnight had submitted a recommendation for him to the principal.

U.S.J. Arc
Midnight is among the U.A. faculty members that Tenya Iida brings back to the U.S.J to stop the League of Villains' assault.

U.A. Sports Festival Arc
Prior to the start of the U.A. Sports Festival, Midnight introduces herself as the chief referee. She warns everyone to play fair while all the students question if her revealing attire is appropriate for a high school event. She demands all of them be silent before she summons Katsuki Bakugo to the podium to lead the pledge. After he finishes, Midnight explains that the preliminary event will be an Obstacle Race around the stadium.

Following the Obstacle Race, Midnight reveals the results and how it translates to the next event: the Cavalry Battle. Midnight explains the rules of the Cavalry battle and its point system, revealing that Izuku Midoriya will be worth the most points since he came in first. While explaining the rules, she is interrupted by Mina Ashido and Ochaco Uraraka. This angers Midnight, prompting her to yell at the girls to allow her to finish explaining the rules. She warns the teams not to knock each other over and allows them to choose their teammates.

When the time for the event comes, Midnight leads the countdown. She allows Minoru Mineta and Tsuyu Asui to hide on Mezo Shoji's back, and when Katsuki uses his explosions to fly away from his team, Midnight allows it because he never touches the ground. Midnight announces when the Cavalry Battle ends and allows Present Mic to announce the placements.

After the lunch break, Midnight announces that those who qualified for the finals will draw lots to determine the pairings for a one on one fighting tournament. She also informs everyone who did not make it may participate in recreational events prior to the finals. She is interrupted when Mashirao Ojiro asks to resign from the finals because he felt he did not play a big enough role in the second round. Nirengeki Shoda feels the same way, causing Midnight to get "turned on" by their naivety. She allows them to resign and says that two members from Team Kendo must fill in their spots. Team Kendo agrees they did not do much in the Cavalry Battle either and allows Tetsutetsu Tetsutetsu and Ibara Shiozaki to take the two open slots.

Midnight oversees each of the matches during the fighting tournament. She is half frozen when Shoto Todoroki creates a giant ice ridge to freeze Hanta Sero. Even so, she does her job and asks if Hanta can move, to which he replies obviously cannot. When Eijiro Kirishima and Tetsutetsu fight to a draw, Midnight announces that their match will be settled via arm wrestling once they recover. Midnight is forced to stop the match between Katsuki and Ochaco when Ochaco's body reaches its limit and she falls unconscious.

During the match between Izuku and Shoto, Cementoss contacts Midnight and asks her if they should stop the match because of Izuku's injuries. During the climax of their bout, Midnight tries to use her Quirk to knock them out, but is knocked off her stand by the explosion at the matches end. Once the smoke settles, Midnight sees Izuku has been knocked out of bounds and announces Shoto as the winner.

When the final match between Katsuki and Shoto concludes, Katsuki angrily confronts Shoto although he has been incapacitated and knocked out of bounds. In order to stop Katsuki's rage, Midnight uses her Quirk to knock him out and restrain him. Midnight introduces All Might to close out the Sports Festival but ends up interrupting his entrance by accident, though she apologizes for it.

Vs. Hero Killer Arc
Following the U.A. Sports Festival, Class 1-A is among those selected by Pro-Heroes to be drafted for internships. Shota requests Midnight come to their homeroom class to help them choose hero names. She has everyone come up with their own names and present them in front of the class, approving or disproving them as they go one by one.

Final Exams Arc
Midnight is featured on a daytime talk show where she talks about the necessity of her need to dress sexily while doing hero work. She explains that she uses a thin costume because, like many others, her Quirk requires exposed skin to work. While talking, she is repeatedly interrupted by Mt. Lady, who is also being interviewed. Eventually, the two come to blows over their ages, much to Minoru's viewing pleasure.

Later on, Midnight meets with her fellow faculty members prior to Class 1-A's final exams. They discuss changing the finals format from facing robotic villains to fighting against the teachers. Midnight comments that this may be too difficult for the students, but they all ultimately agree on the change. Cementoss joins the other teachers at the Final Exams practical portion test site to meet Class 1-A.Midnight is placed against Minoru and Hanta in the ninth match.

At the start of their bout, Midnight uses her Quirk to put Hanta to sleep, and sits at the escape gate with a sleeping Hanta on her lap, much to Minoru's jealousy. Midnight decides to pursue her fleeing student because her sadistic side is aching and whips him as he runs away from her. She criticizes him for running away, but Minoru reveals that his cowardice was just a ploy to fan Midnight's sadistic side and lead her away from the escape gate.

Minoru reveals as a fan of hers, he knows her quirk and has a plan. He comes out of hiding with Hanta's tape wrapped around his mouth to avoid breathing in Midnight's fragrance. She claims he cannot fight her while suffocating, but he uses his Grape Rush technique to stick his spheres to her whip and immobilize her. Minoru runs past her and Midnight admits that Minoru was very impressive. Minoru grabs Hanta and drags him outside the gate to pass the exam.

Provisional Hero License Exam Arc
Midnight, Ectoplasm, and Cementoss join Shota Aizawa in his homeroom class to announce that Class 1-A needs to develop super moves. They move to Gym Gamma where the teachers announce that the students will need special moves for the upcoming Provisional Hero License Exam. Midnight uses Kamui Woods' Lacquered Chains Prison as an example of a super move. Four days later, Fumikage Tokoyami develops his own super move. Midnight advises him to change the name because super moves should be easy to say.

U.A. School Festival Arc
Midnight expresses her concern that Izuku might not make it in time for Class 1A's performance for the School Festival when Toshinori tells her that Izuku received permission to leave school grounds to buy last minute supplies.