Nemuri Kayama, the Pro Hero Midnight, stood tall with a curvaceous figure and striking features. Her long, layered dark purple hair cascaded below her waist, framing sky blue eyes marked by downward-tilting centers, long eyelashes, and a small beauty mark beneath her left eye. Red-painted nails and a preference for dramatic makeup, including reddish-pink lipstick in costume, completed her distinctive look. As a U.A. High School student, her hair was shorter, reaching only her chin. Her hero costume underwent significant evolution. The initial, extremely revealing design consisted primarily of undergarments, protective plates, a dog collar, and an unbuttoned trench coat—a practical choice for her Quirk that ultimately prompted government regulations limiting skin exposure. Her later costume featured a black leather dominatrix-style leotard over an ultra-thin, tearable white bodysuit (flesh-colored in manga), translucent thigh-high stockings attached to a burgundy utility belt, black knee-boots, a red eye mask, wrist cuffs, and accessories like a flogger whip and feather fans. The tearable fabric allowed strategic skin exposure to activate her Quirk while complying with regulations. Midnight projected a complex persona. Publicly, she embodied playfulness, flirtation, and unapologetic provocation, frequently making suggestive comments and displaying comfort with her sexualized demeanor around students. She openly expressed finding youthful idealism or chivalry arousing, famously stating this during the U.A. Sports Festival. This outward behavior sometimes manifested as sadistic enjoyment in confrontations, noted during her final exam battle with Minoru Mineta. Beneath this flamboyant exterior, however, lay a perceptive, articulate, and deeply caring individual. Off-duty or in civilian settings, she appeared ordinary, thoughtful, and even motherly, demonstrating genuine concern for others' well-being, as seen with Pop☆Step in the *Vigilantes* spin-off. She reacted angrily to any implication she was old, stemming from a strong admiration for youthful vigor. Professionally intelligent and strategic, she offered logical justifications for costume functionality and provided insightful guidance to students like Hitoshi Shinso and Momo Yaoyorozu. She held a steadfast belief in her students' potential and demonstrated true heroism and bravery, particularly during the Paranormal Liberation War. Midnight's primary ability was her Quirk, "Somnambulist," emitting a sleep-inducing aroma from exposed skin capable of rendering individuals unconscious almost instantly upon inhalation. Quirk potency increased with greater skin exposure and proved more effective on men than women, though the biological mechanism remained unspecified. Support gear enhanced its effectiveness: feather fans dispersed the aroma widely or directionally, while her flogger-style whips ("Whips of Love") carried traces of the scent. Her combat style leveraged her Quirk strategically for area control and incapacitation, proving highly effective against close-range fighters without respiratory protection. Official stat profiles highlighted her strengths in technique (A) and sexiness (S), with average ratings in power, speed, intelligence, and cooperativeness. She possessed keen tactical intellect for analyzing opponents and situations and held expertise in Modern Hero Art History, the subject she taught at U.A. Midnight attended U.A. High School, participating in the Hero Work-Studies program under the Purple Revolution Agency alongside His Purple Highness. During her third year, she befriended second-year students Shota Aizawa, Hizashi Yamada, and Oboro Shirakumo after encountering them on the school's off-limits rooftop, her favored spot. She played a pivotal role recruiting Aizawa and Shirakumo into her Work-Study, forming "Team Purple Revolution." This period involved collaborative patrols and villain confrontations, including apprehending a Robber Villain and facing the destructive villain Garvey. The latter incident tragically resulted in Shirakumo's death while protecting children, deeply affecting Midnight and her surviving friends. After graduating U.A., she established her own Hero Office with sidekicks known as the Midnight Boys. Before joining the U.A. faculty, Midnight actively pursued cases linked to the Villain Factory and the illegal Quirk-enhancing drug Trigger. She assisted in suppressing Instant Villain outbreaks caused by Kuin Hachisuka and participated in police briefings alongside heroes like Endeavor and Eraser Head. During one briefing at a police station, she helped Aizawa subdue the villain Suicide Bomb. Inspired to guide the next generation and personally recruited by Principal Nezu, she decided to teach at U.A. High School. Furthermore, she successfully convinced the reluctant Aizawa to join the U.A. staff by submitting a recommendation to Nezu. During this pre-teaching period, she continued investigative work, assisting Detective Naomasa Tsukauchi and Eraser Head in tracking Trigger distributors and the emerging threat of bioengineered "Next-Level Villains." Her activities included undercover operations, such as infiltrating mixers where Trigger was distributed, sometimes crossing paths with vigilantes like Koichi Haimawari and Kazuho Haneyama (Pop☆Step). As a U.A. faculty member, Midnight taught Modern Hero Art History. She frequently served as a commentator or umpire for school events, most notably as the chief umpire for the U.A. Sports Festival, where her declarations and reactions drew attention. During the Forest Training Camp, she helped protect students during the League of Villains' attack. Her role expanded into mentorship, particularly guiding students like Momo Yaoyorozu during the Provisional Hero License Exam arc. She played a direct role in student evaluations, overseeing final exams where she battled Minoru Mineta and Mashirao Ojiro. Mineta outmaneuvered her by using tape to cover his mouth and nose, trapping her with his Quirk to pass the exam, showcasing her occasional susceptibility to underestimating opponents due to her sadistic tendencies. Throughout her tenure, she consistently encouraged students to embrace their potential and make decisive choices. Midnight participated in the large-scale operation against the Paranormal Liberation Front. Fighting valiantly on the front lines during the battle at Jaku General Hospital and ensuing chaos, she recognized the impossibility of stopping the rampaging Gigantomachia through force alone. Using her communication device, she relayed a critical strategy to Momo Yaoyorozu, instructing her to create potent sedatives for the Pro Heroes to administer. She urged Momo to act decisively even if it meant bending rules, emphatically stating, "IT'S UP TO YOU! BE STRONG!" as her final known words. While protecting other heroes retreating from Gigantomachia's path, Midnight was overwhelmed by a group of liberated villains, sustaining severe injuries that led to her death. Her sacrifice and final act of trust underscored her commitment to heroism and education.