44th Period Survival Class

(Group A: Kim Do-yun, Choi Won-gyun, Im Seon-ah, Choi Seo-jeong)
(Group B: Kim Tae-hyun, Nam Jeong-woo, Han Su-jin, Choi Na-ri)
(Group C: Lee So-han, Oh Seung-jae, Kim Ji-eun, Im I-ji)
(Group D: Jeon Seok-oh, Seo Ye-rim (Deceased), Choi Yeon-jun, Yang So-hyeon)
(Monsters: Korean Language Monster, Physical Education Monster, Decalcomania Monster, Science Monster, Restroom Mirror Monster, Ball Monster, Nurse's Office Monster, Urban Legend Monster, Anomaly)

(Kim Do-yun: Male, 17 years old. His quick wit allows him to discover that the Decalcomania Monster is sensitive to sound, and he demonstrates the ability to escape crises even in urgent situations, such as surviving by throwing a noisy phone at the Decalcomania Monster when being chased. This ability is also used to strategize against the Urban Legend Monster. He also has a personality that loves to record things, keeping a diary for a year.)

(Choi Won-gyun: Male, 17 years old. A student with a cute and gentle appearance, characterized by his tall stature and slightly chubby build. He has a comedic personality. He is close friends with the protagonist Kim Do-yun and Jung Ji-woo from Class 3. He is in the band club and carries a bass guitar case on his back. He is easily scared and prone to panic.)

(Im Seon-ah: Female, 17 years old. A student characterized by a yellow cardigan, wavy light brown long hair, and golden eyes. Although she tends to cry easily, she is not afraid when venturing out and acts quite calmly according to the rules even in unexpected situations. She has a kind and affectionate personality and is meticulous, carefully recording unusual details on the map. )

(Choi Seo-jeong: Female, 17 years old. A student with brown bobbed hair and a slightly chubby build. While her appearance might resemble Choi Won-gyun's, her paranoid personality makes her the least popular student in Class 1-4 in terms of friendships and reputation.)

(Kim Tae-hyun: Male, 17 years old. A student with blond hair slicked back and red eyes. He is wearing a cast on his right arm for an unspecified reason, and because of this, he wears gym clothes instead of his school uniform. Judging by the fact that he is scheduled to have the cast removed a week after entering the black circle, his injury occurred quite some time ago. He is the second tallest student after Oh Seung-jae (180cm).)

(Nam Jeong-woo: Male, 17 years old. Class president of Class 1-4. When the homeroom teacher is murdered by the Korean Language Monster, he takes on the role of leader in place of the teacher. His reasoning and deduction skills are among the highest of the characters in the story. However, his actions in the story show a subtly weak mental state, as he seems to blame himself for Seo Ye-rim's death among the class members. Judging by his attitude towards the class members, he seems to be a benevolent leader who is kind to everyone, rather than a charismatic leader who commands the class. Also, due to his position as class president, he has encountered the most monsters along with Kim Do-yun, Im Seon-ah, Kim Tae-hyun, and Han Su-jin.)

(Han Su-jin: Female, 17 years old. A student with reddish-brown bobbed hair, red eyes, and a sharp, handsome appearance. She is the second tallest among the female students in Class 1-4, after Im I-ji. Oh Seung-jae, whose life was saved by Han Su-jin, couldn't properly thank her because he was afraid of her. She also doesn't back down from Jeon Seok-oh, who is a delinquent with a strong personality like hers, even cursing at him and acting hostile. This suggests she has a strong and aggressive personality, though not quite a delinquent. Her sharp and intimidating appearance makes even delinquents avoid her, implying that messing with her would lead to trouble. However, she also shows a good side, such as risking her life to save Oh Seung-jae in a dangerous situation and sincerely apologizing to Choi Yeon-jun for her rashness, indicating that while not straightforward, she has a good heart.)

(Choi Na-ri: Female, 17 years old. The shortest female student in the class, with thick eyebrows. Unlike Kim Tae-hyun, who only wears gym clothes on his upper body, she is the only one in the class wearing both gym clothes (shorts) and a top.)

(Lee So-han: Male, 17 years old. A student with black hair wearing a gray hoodie. He is the shortest among the male students. Even in critical situations, he maintains a poker face without showing much emotion, making rational judgments. Except for providing information about the black circle, most of his answers are monosyllabic. However, his actions in the story suggest he is not a bad person.)

(Oh Seung-jae: Male, 17 years old. The tallest and largest male student in Class 1-4, with brown hair and thick eyebrows. He is wearing his school uniform. He sits in the back row and is seen sleeping during the end-of-day roll call in the first episode, suggesting he is a typical ordinary student, neither a model student nor a delinquent. He appears to have an impulsive personality, and his actions tend to precede his thoughts, especially when in danger.)

(Kim Ji-eun: Female, 17 years old. A student with brown hair and glasses. She is in charge of the map in Group C.)

(Im I-ji: Female, 17 years old. A student with green hair and a headband. She is the tallest among the female students in Class 1-4.)

(Jeon Seok-oh: Male, 17 years old. He has black hair and very small pupils, giving him an intimidating appearance. Fitting his looks, he is the third tallest student in the class, after Oh Seung-jae (180cm) and Kim Tae-hyun, and plays the role of a delinquent. Basically, like a delinquent, he engages in many deviant behaviors such as drinking and smoking, and has a belligerent and rough personality.)

(Seo Ye-rim: Female, 17 years old. A timid student who wears glasses. As she was the closest witness to the homeroom teacher's death, she is seen crying or with a pale face in the story. Despite her weak personality and rather petite build, she is the third tallest among the female students, after Im I-ji and Han Su-jin.)

(Choi Yeon-jun: Male, 17 years old. A student with dull purple hair and lifeless purple eyes. He wears a white and purple top over his school uniform, and his bag is also purple. Like Lee So-han, Yang So-hyeon, and Kim Tae-hyun, he shows very little change in expression. He shows only slight shock when he sees the school transformed into a giant maze due to the black circle, and except for sweating profusely with trembling pupils when seeing the Toilet Mirror Monster copy Seo Ye-rim's appearance and laughing while talking to Jeon Seok-oh, he is almost always expressionless.)

(Yang So-hyeon: Female, 17 years old. A student with gray medium-length hair and gray eyes, wearing a hooded zip-up over her school shirt.)

(Korean Language Monster: The first monster encountered by the protagonist's group, Class 1-4. It has very long arms and sharp fingernails. It is the embodiment of the short-haired female character drawn in the Korean language textbook, combined with the school rule that 'students do not wander outside the classroom during class.' It severely scolds and decapitates with a hand chop anyone found outside the classroom during class hours, but does not attack those within the classroom. It actually killed only the teacher who was outside the classroom and then left, watching the protagonists inside the classroom with a smile without attacking them. It did not appear at all during break times.)

(Science Monster: The monster is the embodiment of various experimental equipment in the science lab combined with the 'Safety Rules for Science Laboratories.' Its upper body is a Erlenmeyer flask, its lower body is an alcohol lamp, its arms are test tubes, and its legs are tripods. It wears a lab coat over its upper body. Although its appearance suggests it cannot move, it can actually walk slowly on its tripods, and it is so tall that Oh Seung-jae, the tallest student in Class 1-4, has to look up considerably to see it. It is the main culprit behind the annihilation of Class 1-1.)

(Anomaly: Discovered first by Class 2-1, not another class, suggesting that anomalies are easily observed from the perspective of Class 2-1's classroom. It is the indirect cause of the deaths of two students and the disappearance of the other two, as it isolated Group A in the nurse's office and simultaneously collapsed the curtains blocking the maze, allowing the Nurse's Office Monster to escape. It is also the main culprit behind scattering Class 1-4.)

(My Ball Monster: The appearance of the monster in the story is, for some reason, limited to soccer balls, basketballs, and volleyballs. The My Ball Monster usually just says 'pass' and 'my ball,' and has no aggression, but when thrown by the Physical Education Monster or when a whistle is blown, it becomes aggressive and attacks people not wearing gym clothes, similar to a zombie. If the Physical Education Monster points to a person bitten by the My Ball Monster while blowing a whistle, that person's head also turns into a My Ball Monster, and the Physical Education Monster detaches the head of the transforming human into a My Ball Monster.)

(Nurse's Office Monster: It is presumed to be the embodiment of the nurse's office rules, such as 'The nurse's office bed area can be used for health issues like headaches and stomachaches,' combined with the nurse character and treatment actions depicted in posters and other visuals in the nurse's office. Inside the nurse's office, there is a maze made of beds and curtains. Those who wander in this maze for a certain period experience dizziness and vomiting. At this point, the curtain leading to the Nurse's Office Monster's area opens. The monster resembles a female nurse wearing a white doctor's coat and a white mask, with oval eyes with eyelashes. It is tall, and like the Korean Language Monster and Physical Education Monster, it has very long arms. Its nose is a thick, short pink line. When it appears, there is a smell of blood and disinfectant.)

(Urban Legend Monster: Presumed to be the embodiment of the 'Urban Legend of the School Broadcasting Room.' It broadcasts through speakers like a real school broadcast and mesmerizes those who follow the broadcast's content. It is the main culprit behind the sacrifice of half of Class 2-1's students from the beginning.)

(Physical Education Monster: The monster is the embodiment of the physical education teacher's appearance combined with the school rule that 'gym clothes must be worn during physical education classes.' As the rule seems to be limited to the gymnasium, it does not appear to leave the gym. Its appearance is that of a normal physical education teacher with appropriate attire, but its face is shadowed, with only large eyes and a gaping mouth visible. It holds a red whistle in its mouth. It is also quite large with extremely long limbs and large hands. Its athletic abilities are very high, befitting a physical education subject, and it shows immense strength. Furthermore, as a monster close to human form, it is quite intelligent and cunning, utilizing the surrounding terrain or lulling its opponents into a false sense of security. It is the main culprit behind the additional sacrifice of three survivors from the remaining half of Class 2-1.)

(Toilet Mirror Monster: Presumed to be the embodiment of the 'Urban Legend of the School Restrooms.' It is the main culprit behind the first student casualty from Class 1-4. It shows distorted reflections of Jeon Seok-oh, Choi Yeon-jun, Seo Ye-rim, and Choi Seo-jeong in the mirror, and then pulls Seo Ye-rim into the mirror world, releasing a doppelganger. The doppelgangers have their front and back reversed, like their mirror images, with the school uniform buttons on the opposite side. The doppelgangers have a limited range of movement. The moment a person is pulled into the mirror by their doppelganger, they lose control of their body to the doppelganger. In the story, Seo Ye-rim's doppelganger rushed towards Jeon Seok-oh's group but hit an invisible wall. At this point, Seo Ye-rim was blocked by the mirror's bathroom wall and hit it, and the doppelganger was also unable to move forward due to this effect.)

(Decalcomania Monster: A monster that folds the walls and floor of the hallway with its giant hands, turning them into drawings. It appears to be the embodiment of the art subject, specifically the decalcomania technique, combined with the school rule 'do not make noise in the hallway.' Due to its method of folding walls to turn people into drawings, it is referred to as the 'Wall-Folding Monster.' When the monster's hands touch the hallway walls or floor, they transform like paper torn from a sketchbook. It uses this to hide behind walls and attack victims by folding the wall when they make noise, or by turning the floor into paper and chasing them as it folds. It roams even during break times and is a monster born from distorted school rules. In the story, it appears as a bulging shape hidden behind a wall with only one arm visible. When it detects noise, it makes a sound like "Decalcomania?" and moves towards the source of the noise. It is sensitive to sound rather than sight, and victims folded by the Decalcomania Monster are imprinted as drawings on both folded sides. As of Part 1, it is the largest monster that has appeared. It is the main culprit behind the annihilation of Class 1-3 and the cause of the most casualties in Part 1.)