Nemuri Kayama (
Nemuri is a tall, curvaceous woman with sky blue eyes, which tilt downwards in the center; framed by a set of rather long eyelashes. She has abundant spiky dark purple hair which is made up of layers of varying lengths, the longest ones reaching down below her waist. Her chin-length bangs that are 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 has a small mole under her left eye.
Her hero costume is very similar to one of a traditional dominatrix. She wears a black leather breastless leotard over a white bodysuit (flesh-colored in the manga), which emphasizes her breasts, body and legs, the leotard possessing red gemstone-like accessories in a vertical pattern from the collar to the midriff. She also wears translucent black thigh-high stockings and black knee-boots. She has a small, red mask outlining her eyes, a handcuff on each wrist, and a red utility belt decorated with gold studs around her hips, a matching pentagonal buckle in its center. She is often seen carrying a flogger-style whip. The white bodysuit is made of thin material that is easily rippable so she can more easily use her Quirk. Nemuri has stated in an interview that she is trying different materials to find out what works while adhering to regulations.
Midnight is a very playful and flirtatious person with a unpredictably serious and temperamental side to her. She gets angry whenever someone interrupts her or when they insult her, and, when it comes to insults, she is especially sensitive about her age.
Midnight has no shame for dressing or acting sexually in front of young students and appears to act on whims most of the time. When she accepted Mashirao Ojiro and Nirengeki Shoda’s request to resign from the tournament, she commented that their naivety "turned her on". She was also very excited to see the chivalry displayed by Eijiro Kirishima during the tournament when he shook Tetsutetsu Tetsutetsu’s hand.
When Class 1-A needed to decide on code names for their internship, Midnight displayed her willingness to help her students by making sure they chose names that would represent themselves well. During the Final Exams, Midnight admitted to Minoru Mineta that she has a sadistic side and enjoys dominating others. She can be impressed with those who resort to genius plans, as she was amazed by Minoru using tactical thinking to defeat her by leaving her in place before passing the gate.
Despite her flirtatious personality, Midnight is intelligent, perceptive, and articulate, as seen when she logically explained the reasoning behind some hero's having revealing costumes to make full use of their quirks, and how that lead to "sexy" costumes and how she single handedly instituted the costume regulations. Mt. Lady replied that it's because she likes dressing way she does. Her love of "youth" is also a reason she gets angry when someone mentions her age or calls her old.
Whip: Fitting her dominatrix theme, Midnight wields a flogger-style whip in combat and she is skilled in wielding it. She also used a bullwhip-style whip during the First Term Final Exam.