Here's a list of all the characters that have been introduced and maybe a few secrets/hints that have been mentioned in the story so far, just in case you readers get confused~ 

If anyone new appears, I'll add them to this list!

Main Characters

Jung Juyeon: the main character. A sarcastic, more-than-a-little y overachiever who accidentally discovers the existence of Problem Children. Although originally only accepting her fate as a means to get a reference letter for any university she wants, she has started to genuinely like her situation and classmates. As of the latest chapters, she's become a little more mellow and is learning to accept and express her feelings. There is a trauma between her and her parents which has yet to be revealed, but she doesn't like talking about it.

Park Sumi: Juyeon's roommate, a pink-haired girl who's as tough as nails. Although she originally was rather antagonistic towards Juyeon, it's recently been revealed that she too is a human, and that she had been sent to High Class just like Juyeon for discovering the existence of PC when she was a child. She is friends with and grew up with many of the Exo and especially Sehun (who was the one who revealed the existence of PC to her in the first place, and thus the reason why she's even in High Class), but until befriending Juyeon had strayed away from the Exo and stuck with her own group. She is very protective of Juyeon and they have since become best friends. It's been revealed that her parents are some sort of council members for the Academia, and vaguely implied that they knew about the existence of Problem Children.

Exo: The most powerful Problem Children of their generation and essentially the rulers of High Class

Sehun: the first PC Juyeon encountered; a grumpy, cold, and occasionally dangerous boy with the power of wind. He had the worst relationship with Juyeon at the start, constantly threatening and at one point even physically attacking her, although they seem to have gained a deeper understanding of each other. He really doesn't like seeing girls cry, and was the one who brought Sumi to High Class accidentally when he befriended her as a child. He gains a lisp when flustered, to the peril of anyone who laughs.

Kai: a charming, laidback guy and serial flirt, with the power of teleportation. He enjoys teasing and flirting with Juyeon and any other girls he sees, regardless of their reaction, although there have been several moments where it's been hinted that he's much sweeter and shy than he appears. As of the winter dance, Sumi has flat out stated that most of Kai's words and interactions are a mask, one that he's been wearing for almost his entire life. He and Chanyeol form the "Idiot Duo".

Suho: the helpful class representative with power over water. Although very friendly and polite (compared to the others) and despite being a natural leader, he's shown to be rather selfish and only caring for his own group of friends, showing disinterest and sometimes even manipulating anyone else. He's one of the only two Exo members to be shown visibly fighting against the closed-off world of PCs and trying to understand and even empathize with normal sensibilities. As of the latest chapters, he has been sent to detention for the first time, and it's yet to be revealed how much this has had an effect on him.

D.O: a quiet, gentle boy with a hidden temper and control over the power of earth. He's one of the nicer and more sensible Exo members, although it has been shown that he can be just as dangerous and uncontrollable as the others. He tends to stay silent and only speak when necessary, although lately he's been opening up more to Juyeon. Like Suho, he has been shown questioning the world of PCs and trying to understand the normal way of things. It's been revealed that his real name is Do Kyungsoo, although due to some private reason he has cast away that name and becomes extremely angry if anyone mentions it.

Baekhyun: a sweet, charming guy with the power of light. Like his power, he appears harmless at first, but can be quite threatening and dangerous if given enough incentive. He was the first to befriend Juyeon of all the Exo, and is generally one of the friendlier members. He has been shown to care deeply about how Juyeon thinks of him. In the beginning of the story, he had given Juyeon a very fancy, expensive pen, and seems uninterested and even insistent on not taking it back. Time will tell if this plays a bigger role later on.

Chanyeol: a goofy, mischievous prankster who likes nothing more than to mess around, which doesn't bode well when he's got control over the power of fire. He gets significantly more awkward and clumsy around Juyeon, but the two of them seem to have fun together and surprisingly get along rather well. He's been to detention the most times out of the Exo, which may or may not have affected him permanently in some way. He and Kai form the "Idiot Duo". 

Other Students

Seoyeon: a PC with the power over calculations and statistics, which is considered a very weak power but one Juyeon personally finds useful. She's one of the two PC outcasts Juyeon sits with for meals and has since become almost a friend. While shy and nervous at first around new people, her normal personality is actually rather outgoing and sassy. She's best friends with Minjun.

Minjun: a PC with the power to see events of a person's past by looking into their eyes. His hair is very shaggy and covers his eyes specifically to help block out his ability. He's one of the two PC outcasts Juyeon sits with for meals and has since become almost a friend. He's a rather calm, quiet person, and is best friends with Seoyeon.

Kim Taehyuk: leader of a (literally) underground gang of rebels that are anti-Exo and anti-Academia. He's one of the few students who sees all the problems with High Class and what it does to the young PCs, and as such also hates the Exo for simply being a product of the Academia's ways and being completely loyal to the principal. All of his free time is spent in his underground "base", and he has invited Juyeon to join him in finding a way to fix everything High Class has done.

Jun: Taehyuk's second-in-command with the power over mind control. He has a personal vendetta against Exo for killing his sister during an Extracurricular Activity gone wrong (it's been heavily implied that the killer was D.O, too). Although he seemed to be a grumpy, angry person at first, outside of Taehyuk's base he is shown to be much more awkward, even using his powers to communicate with Juyeon instead of actually talking to her.

Shim Minah: leader of the Exo groupies with the power of precognition, being able to see a little into the future. She and the groupies verbally attack Juyeon any chance they get for being friends with Exo, with not much success or even any reaction from Juyeon besides disdain. Recently, Minah has become much more tolerant of Juyeon after Suho's first detention, and she seems grateful that Juyeon was there to support Suho. Time will tell if the groupies ever truly back off.

Kwon Daeri: a member of the Exo groupies with the power of clairvoyance, able to see anything she wishes so long as it's happening in the present. A tiny, timid girl who seems the least antagonistic towards Juyeon, and has even helped Exo find her before. She may or may not have used her powers to peek on Exo in the shower.

Kim Jonghyun: an upperclassman with the power of super-speed. He fought against Baekhyun during an Extracurricular Activity and got horrifically injured, which Juyeon feels tremendously guilty about (since it was, in a roundabout way, her fault). He's a nice, cheerful guy who's friends with Juyeon's classmates: Key, Minho, and Taemin. Juyeon gets very flustered around him, to her extreme embarrassment.

Key: one of Juyeon's classmates and can create force fields. While snarky and dramatic, he seems to genuinely like Juyeon, and the two have become good friends. While he's uninterested in getting tangled in with all the Exo drama, he is very interested in watching Juyeon's relationship with the Exo play out.

Onew: an upperclassmate and one of Key's friends. His power is unknown. He's clumsy but well-meaning, and he seems to have a good enough friendship with Juyeon to dance with her during the winter dance.

Taemin: one of Juyeon's classmates, with an unknown power. He's cheerful and empathetic, and seems to have a good enough friendship with Juyeon to dance with her during the winter dance.

Minho: one of Juyeon's classmates, an easygoing guy with an unknown power. While he apparently threatened Juyeon on her second day in High Class, he has since become good enough friends with Juyeon to dance with her during the winter dance. 

Yoona: her power is unknown. She used to date Yong Sangyoung before breaking up with him after she thought he cheated on a test. The personalized button she gave to him was the clue Juyeon and the Exo needed to kickstart the mystery arc.

Yong Sangyoung: his power is unknown. He originally dated Yoona as a dare before genuinely falling for her, but she broke up with him for cheating on a test. He was blackmailed by Taehyuk to throw a rock through Class 44's window, creating the mystery arc. He and Jun used to be good friends (it was Jun, in fact, who dared him to date Yoona in the first place), but it's been assumed they had a falling out when Jun joined up with Taehyuk's gang.

Park Suji: a normal that was one of Juyeon's closest friends before she was sent to High Class. Suji has been revealed to actually be Sumi's twin sister, and that they had been separated since childhood. Ever since, Suji had been attempting to find a way into High Class to find her. She's sarcastic and bitter, and much like how Juyeon used to be. She has a particular hatred towards Donovan for taking Sumi away.

Academia Staff

Principal Donovan: the principal of Academia Mysteria and in charge of everything in High Class. He's an easygoing, rather kind man that many of the PCs are loyal to. The Exo and Sumi in particular are devoted to him and willing to follow his every order, although it's unknown how that feeling has changed since Juyeon arrived. He seems to have a strange relationship with Sumi and Suji, considering he was the one who had to take Sumi away and bring her to High Class. Sumi has been frequently called Donovan's "pet student". Although he and Juyeon get along well, Juyeon has recently voiced her suspicions to Donovan, confronting him on whatever his ulterior motives are for the Exo and High Class. 

Professor Strange: Class 44's homeroom teacher and their History professor. He is a sharp, no-nonsense man who seems to particularly dislike the Exo.

Professor Terror: the Science teacher. She's a rather unstable woman who has a particular delight in dangerous chemicals, explosions, and dissections on animals that are still alive.

Professor Struggle: the English teacher. She's an elderly woman who is the kindest out of all their professors, but seems to have a bad enough reputation that the PC students don't try to cross her.

Professor Horror: the Mathematics teacher. He has a very short temper and penchant for throwing chalk.

Professor Pain: the coach of the PC training classes. He's a dangerous, short-tempered man akin to a drill sargeant who seems to want to endanger Juyeon the most out of any of the teachers. He rather openly fantasizes about finding a way to kill Juyeon during training sessions.

Professor Fear: in charge of the PC therapy sessions. She's a young, bubbly woman Juyeon compared to a "typical college dance major", but she seems to have some sort of PC power over reading thoughts or finding someone's inner turmoil, as she was able to correctly identify Juyeon's past with her parents. She has taken an interest in Juyeon and frequently invites her for free "sessions", and Juyeon particularly dislikes her.

Takahashi: a gentle, soft-spoken Japanese man and High Class' nurse. The Exo have taken to affectionately calling him "doc", despite his frequent attempts at telling them he's not actually a doctor.