Tsumugi is a young woman, who is a self-described plain-looking college student of a rather tall height and fair complexion. She has knee-length teal-blue hair parted in the center, straight and smooth at the base and gradually splitting into waves near the tips. Her eyes are large, round, and a soft teal-green color. She wears round, rimless glasses with white temples. Her clothes consists of a white blouse with an orange bow tied at her collar underneath a two-button, pocketed, teal-black school blazer adorned with two silver buttons on each lapel and a single button on each gorge. She has been shown without her blazer in her promotional artwork, which shows the insignia of her favorite fictional school in black on her left breast. She wears a knee-length pleated skirt the same color as her blazer with two dark teal stripes lining the hem held by dark gray suspenders. Her legwear consists of dark navy knee-length socks and teal-gray loafers. Tsumugi is an honors type student who speaks in a docile and gentle way, but she becomes very passionate when she talks about her favorite series or cosplays, having a habit of slipping infamous quotes from various sources into the conversation. Being a self-proclaimed introvert, she also tends to ignore people while she's in her thoughts, no matter how many times they try talking to her, and appears rather distant at times. She tends to call herself and everything that she has done "plain," as she believes that among all of the students, she is the one who has the plainest appearance and personality. She uses the word repeatedly and sometimes appears even offended if someone else tries to argue that she isn't plain. She understands that some people might not recognize her as the Ultimate Cosplayer since her plain appearance conceals her talent. While Tsumugi is the Ultimate Cosplayer, she only enjoys making costumes, not wearing them, as she is not really fond of people looking at her. However, she hates using cosplayers who care more about standing out than the love of the characters, so she wears her own costumes as well but with love. She deeply loves cosplaying as she states that cosplaying is an expression of love. She has deep respect for fictional characters and gets very offended if they are disrespected. Despite her status as the Ultimate Cosplayer, Tsumugi actually doesn't have interest in cosplaying herself. Rather, she states that she enjoys recreating costumes more. She loves to create costumes because it is like making a fictional character real, in a way. She also has a sponsorship that makes her can create costumes with expensive materials. She is also a well-versed otaku in anime and manga references. In her promotional artwork, Tsumugi is featured with mannequins wearing lingerie and a wig, several paints and cosmetic brushes, as well as red thread and an object which could be interpreted as scissors. This could imply that her talent is multi-faceted. Tsumugi is somewhat timid, and she is usually the first person who screams whenever something scary happens. Another notable trait of hers is that she is somewhat pessimistic. Furthermore, whenever someone else has a some sort of character establishing moment, she tends to act threatened and inferior, as she closes her eyes and puts her hands up in slight defense while she squeals something about how much more interesting, stronger, cooler or pure the other person is compared to her. Regardless, she generally appears to be a kind person, However, she also seems to be very skilled with blending in her environment. She constantly changes her mind and follows any decisions made by the majority, even if she doesn't have any actual reasons for it. In any occasion, she tends to react to even the most minor things said by the others. Notably, despite her somewhat timid and plain personality, she actually has the ability to take control in the few situations she wishes to. Despite her plain and docile attitude, she ia actually quite perverted, as she is a big stereotypical fan of anime and manga. She even takws "special art commissions" and has "favorite pillowcases" she buys. She also wonders if she could wipe her entire hard drive at home from anywhere in case somebody tries to search her computer, worrying about the pictures that were saved on it. She seems very intent on keeping this side of her hidden, as she very rarely brings it up or acknowledges it to anyone.