Male, 17 years old. Group A. He has black hair and blue eyes. He is quick-witted and has a personality that loves recording things.

Female, 17 years old. Group A. A student characterized by a yellow cardigan, wavy light brown long hair, and golden eyes. Although she has a crybaby streak, she doesn't get scared once she starts exploring and acts quite calmly according to the rules even in unexpected situations. She is kind and gentle, with a delicate personality that involves meticulously recording special notes on maps.

Male, 17 years old. Group B. A male student with blonde slicked-back hair and red eyes. For some reason, he is wearing a cast on his right arm, and his top is a gym uniform instead of a school uniform. He is close to Nari and hangs out with her. Is he blunt?

Male, 17 years old. Group B. His mental processing and reasoning abilities are among the highest of all characters. He occasionally shows a surprisingly weak mental state. Judging by his attitude toward his classmates, he seems to be the type of virtuous leader who is kind to everyone rather than a charismatic type who rules the class.

Female, 17 years old. Group B. The shortest female student in the class with thick eyebrows. Unlike Kim Taehyun, who only wears a gym top, she is the only one in the class wearing both top and bottom gym clothes. She is best friends with Taehyun and they are always together.

Male, 17 years old. Group C. A student with black hair wearing a gray hoodie. He is the shortest among the male students. Even when an emergency strikes, he maintains rational judgment with a consistent expressionless face without showing much emotion, but he is depicted as not being a bad-hearted student.

Female, 17 years old. Group C. A female student with brown hair and glasses. She is in charge of the map in Group C. She showed her prowess by noticing that the lengths of class time and break time were swapped due to the characteristics of the Black Circle.

Male, 17 years old. Group D. Black hair and black eyes. The delinquent position. Basically, like a delinquent, he engages in many deviant behaviors such as drinking and smoking, and has a bellicose and rough personality. He is close friends with Hyunjun. He often acts as the leader of action, fitting for a delinquent character. He is a character with two sides, sometimes showing a decisive side.

Male, 17 years old. Group D. A male student with dull light purple hair and purple dead eyes. He wears a white and purple top over his school uniform. He is almost expressionless except for smiling while talking to Jeon Seoko. Unlike Jeon Seoko, who gets into conflicts with other students due to his rough speech, he showed perfectly normal behavior, such as mediating conflicts between Jeon Seoko and other students.

Female, 17 years old. Group D. A female student with gray medium-length hair and gray eyes, wearing a zip-up hoodie over her school shirt. Even in a situation where the school has fallen into a hole, she maintains rational judgment with almost no change in expression. Her nickname is Yangso. She is close friends with Seona. It is said that only Lim Seona calls Soyeon by her first name.