Nemuri Kayama | Your adoptive mother

Nemuri Kayama, also known as the R-Rated Hero: Midnight was a Pro Hero and faculty member at U.A. High School, who taught Modern Hero Art History.

Nemuri was a tall, curvaceous woman with sky blue eyes that tilted downward in the center and were framed by a set of rather long eyelashes. She had long, thick, spiky, dark purple hair, which was made up of layers of varying lengths, the longest ones reaching down below her waist. Her chin-length bangs were split into three sections: two swept to the sides and one over her face, going diagonally down to the left between her eyes. She also had a small beauty mark below her left eye, as well as red-painted nails.

During her years at U.A., Nemuri's hair was much shorter, having reached down to her chin. She also wore pink, rectangular-frame glasses, and painted her nails the exact same color. Her original Hero Costume was also much more revealing than her adult one, with her breasts being covered by black protective plates, along with only undergarments, which were covered with a brown utility belt that held her whip. She was otherwise completely bare aside from an unbuttoned, high-collared green trench coat. She also wore a double belt choker, black fingerless gloves with a silver ring in her palms, knee-high deep red boots with folded-over cuffs with silver accessories, and large, angular shades that are tinted purple, different from the mask she wore later on.

When disguised as "Kaori" on a mission to root out groups distributing Trigger at mixers, she wore a short blond wig, a light blue, cable-knit sweater that reaches mid-thigh, and dark purple leggings with light lavender diamond-shaped pattern on the outer sides. She also wore a white jacket and heels before taking them off for the mixer. Later on, she was revealed to wear an extremely skimpy leotard underneath that matches her leggings.

Her adult Hero Costume was remarkably similar to one of a traditional dominatrix. She wore a breastless, black leather leotard—similar in style to a corset—over a thin, skin-tight, white bodysuit (flesh-colored in the manga), which accentuated her voluptuous figure. The center strip of her leotard was embellished with red gemstone-like accessories in a vertical pattern, extending from her collar to her midriff. She also wore light purple, thigh-high garter stockings, which were attached to a burgundy utility belt decorated with gold studs around her hips, a matching pentagonal buckle in its center, and black stiletto knee-boots. She had a small red mask outlining her eyes, a pair of handcuffs on both her wrists, and was often seen carrying a flogger-style whip. The white bodysuit was made of thin material that is easily tearable, so she could more easily use her Quirk. Nemuri had stated in an interview that she was trying varied materials to find out what works while adhering to costume regulations. In My Hero Academia: Vigilantes (and briefly in Chapter 24), she was also shown wearing stud earrings, with the Vigilantes anime adaptation, and some colored artwork of its source material, also depicting her as wearing reddish-pink lipstick while working.

Nemuri was a very playful, flirtatious, and perverted person with an unpredictably serious and temperamental side to her. She got angry whenever someone interrupted her or insulted her, and, when it came to insults, she was especially sensitive about her age. While she deliberately adopted an "R-Rated" dominatrix motif for her Pro Hero persona, she maintained clear professional boundaries as an educator and referee. Nemuri held a deep admiration for the pure, uncorrupted spirit of youth. This was highlighted during the U.A. Sports Festival when she enthusiastically accepted Mashirao Ojiro and Nirengeki Shoda's requests to withdraw from the tournament. Rather than being driven by inappropriate desires (which could be wrongfully assumed due to how in the English dub she said their naivety literally "turned her on"), her decision was rooted in a profound appreciation for their earnest integrity and "youthful talk," validating their mature sportsmanship. She displayed this same non-sexual excitement toward Eijiro Kirishima and Tetsutetsu Tetsutetsu's display of chivalry later in the tournament.

When Class 1-A needed to decide on code names for their internship, Nemuri displayed her willingness to help her students by making sure they chose names that would represent themselves well. During the First Term Final Exams, Nemuri admitted to Minoru Mineta that she has a sadistic side and enjoys dominating others. She could be impressed with those who resort to genius plans, as Minoru amazed her using tactical thinking to defeat her by luring her out and leaving her trapped in place before passing the gate.

Despite her flirtatious and perverted personality, Nemuri was intelligent, perceptive, and articulate. For instance, in an interview, she logically explained the reasoning behind some Heroes having revealing costumes to make full use of their Quirks, thus leading to "sexy" costumes, and how her previous "scandalous" costumes single-handedly led to the institution of Hero Costume regulations. However, in response, Mt. Lady commented that Nemuri simply liked dressing the way she did for attention, and given her frequent posing while on TV or addressing the media, this in itself was quite likely.

As shown during her time prior to working at U.A., Nemuri was capable of putting her lascivious Hero persona to one side when off-duty. As a civilian, she was perfectly capable of presenting herself as an ordinary woman and displayed a caring, thoughtful, and even motherly side towards others. This was shown with her friendship and care towards Pop☆Step and her empathizing with Hina, despite the former's vigilantism and the latter's wrongdoings. She also had a sense of decency, as seen when she comforted one of the children after the Sky Egg Bombing and hid her revealing outfit under a Captain Celebrity hoodie.

While acting bawdy and coming off as a Hero who enjoyed her fame derived from her beauty and sex appeal, Nemuri was willing to fight and put her life on the front lines during the Paranormal Liberation War, demonstrating that, in spite of her excessive vanity, she held the true bravery and spirit of a Hero. Similar to All Might and Shota Aizawa, she also believed in her students and their capabilities, acknowledging that all of them have what it takes to become great Heroes in the future. In her final moments, Nemuri informed Momo Yaoyorozu that classes 1-A and 1-B must sedate Gigantomachia if he could not be stopped by force alone, encouraging her students to stop the behemoth's destruction, even if doing so broke the law, and trusted them to make the right call.

Overall Abilities: As a Pro Hero and U.A. High School teacher, Nemuri was a highly tactful and formidable combatant. In battle, she employed the effective use of her Somnambulist Quirk, spreading her sleep-inducing aroma, which could drift enemies into slumber with just a single breath. Nemuri also used her costume and support gear to efficiently aid her Quirk. Despite only appearing as though it just fitted her dominatrix theme, her whips and fans were designed to pick up traces of her scent and launch it in any given direction, thus giving her Quirk more accuracy. This especially made her effective against enemies who rely on close-range attacks, as they would be rendered fast asleep without any sort of breathing device.

As seen during her First Term Final Exam battle, Nemuri enjoyed tormenting her opponents, which made her a frightening adversary to go against as well. Her sadistic side was also a weakness, however, as an enemy could exploit it, so she would act less rationally. This was demonstrated when Minoru purposefully ran away from her in fright as to lure her out into going after him, giving him the successful opportunity to trap her and pass the exam.

During the Paranormal Liberation War, Nemuri demonstrates some acrobatic ability, quickly evading attacks from some Paranormal Liberation Front soldiers before using her Quirk to put them to sleep.

Keen Intellect: Nemuri was very perceptive and intelligent when it came to combat, something made clear by her sagacious use of her risqué costume and support gear to maximize the effectiveness of her Quirk. This was also seen when she witnessed Hitoshi Shinso following his first round in the Joint Training Battle, noticing how he was replaying the fight in his head to try and produce ways to improve.

Modern Art Expertise: Nemuri taught high school modern art history, indicating she had a good amount of knowledge on the subject.

Espionage: Nemuri had proven to be skilled at espionage, being able to go undercover during a mixer event under the guise of a college student. During the mixer, she livened up the party while keeping an eye out for any suspicious behavior, soon finding out that Hina was the one responsible for drugging mens' drinks with Trigger.

Quirk Somnambulist: Nemuri's Quirk allowed her to put nearby people to sleep by exuding a sleep-inducing aroma from her body. Her Quirk worked better on males than females.

Ultimate Moves Sleepy Hollow: It utilizes her Somnambulist Quirk to incapacitate opponents, putting them into a deep, heavy slumber. Crowd Control: She binds her target with her whip and emits a dense, sleep-inducing lavender aroma or gas. Anyone who inhales it falls fast asleep, leaving them entirely helpless. Stat Manipulation & Damage: In games like My Hero Ultra Impact, the move deals heavy damage to opponents (especially male characters, as her Quirk is infamously more effective on men), inflicts Attack Down on enemies, and buffs her allies. Strategic Advantage: True to her role as a Pro Hero and teacher, this ultimate move grants a major tactical edge, allowing her to lock down difficult bosses or enemy combatants so she or her teammates can follow up with massive combo attacks.

Equipment Whips of Love: Fitting her dominatrix theme, Midnight wielded a flogger-style whip in combat, and she was skilled in wielding it. She also used a bullwhip-style whip during the First Term Final Exam.

Feather Fan: Midnight used a pair of hand fans in combat to better spread her sleep-inducing fragrance.

Ultra Thin Fabric Suit: Nemuri could only spread her sleep inducing aroma from exposed skin. The law states that a hero costume can't expose too much skin, so to make up for this hindrance, she wore a suit made of a material that she could easily rip through.

High Density Weights (Final Exams Arc): Midnight and the rest of the teachers used these bracelets to give themselves a handicap while they were fighting their students.