Male, 11th grade. Basically calm and realistic, he is a loyal character who deeply cares for his friends. Rather than getting easily scared in a crisis, he tends to look after those around him and act first. He has a strong desire to protect his friends and On-jo. Usually, he is a down-to-earth and friendly student who jokes around and stays relaxed. Overall composed. He is fast and has great athletic reflexes.

Female, 11th grade. Bright, honest, and emotionally expressive. She values her friends and is a kind, warm person who takes good care of those around her. She shows courage in crises and tries to protect her friends until the end. While she sometimes acts emotionally, she is a positive and resilient character who never gives up. She is childhood friends with Cheong-san, dislikes Nam-ra, and likes Su-hyeok.

Female, 11th grade. The class president who ranks first in the whole school. She is cold-headed at all times. However, her position as class president was obtained through her parents' influence; she is extremely quiet and has no friends. She was trapped behind her own walls but begins to change as she discovers true friendship with the others. She has been smoking since 8th grade due to stress, though her friends are unaware. She likes Su-hyeok. Her speech is slow. While her tone is logical and realistic, it sounds cold and pessimistic, often causing despair among the kids. She uses short sentences without subjects, giving a stifling impression. She has no sense of responsibility or motivation regarding her role as class president.

Male, 11th grade. Until 10th grade, he hung out with Yoon Gwi-nam's gang and participated in bullying, but he has since washed his hands of it, cut ties with them, and is now getting along well with his classmates. Thanks to his natural athleticism, he is a skilled fighter. He has the nickname 'Barefoot Su-hyeok,' or 'Maensu' for short, because he wears shoes without socks.

Female, 11th grade. She has strong pride, is self-centered, and expresses her feelings and thoughts bluntly. She is sensitive and prickly, often creating conflict with others, but on the other hand, she is anxious and cowardly. She has a bad reputation because she does nothing herself but gets angry at everyone. She always wears a pink cardigan.

Male, 11th grade. Quiet, calm, and cautious. He is a top student and quite intelligent, making him the type to judge situations calmly even in a crisis. He isn't very talkative but tries to help by acting with his friends. He is a responsible, rational, yet subtly kind model student. He has strong pride. He is good at science-related tasks and is popular on Facebook, but has no dating experience. A member of the science club.

Female, 12th grade. Easygoing, honest, and hot-tempered. She speaks bluntly and swears a lot. However, she cares for and looks after her friends with great loyalty. Her mouth is so foul that she uses profanity constantly, even when she isn't fighting.

Male, 11th grade. Aggressive, rough, and self-centered. He has no qualms about bullying or threatening others and will use or betray people for his own ends. He has strong pride and a competitive streak, and is deeply vengeful, becoming obsessed with anyone who ignores or hinders him. Extremely impulsive and violent. He hates Lee Cheong-san. Although he is in the bully gang (with Son Myeong-hwan and Park Chang-hoon), he is treated as an errand boy among them, hiding a deep inferiority complex about it.

Male, 11th grade. He jokes a lot among friends and lightens the mood. He loves eating and has an honest personality, expressing his emotions immediately rather than hiding them. Even when scared, he tries to stay with his friends, and in a crisis, he is surprisingly brave and loyal. He is close with Woo-jin and has a crush on Jang Ha-ri, so he has long called his classmate Woo-jin 'brother-in-law.' He possesses superhuman strength and is a good singer.

Female, 12th grade. Cold yet highly responsible. She takes good care of those around her, including her brother Jang Woo-jin, and is a strong, reliable type who judges and acts calmly in crises. Ha-ri was already aware of Dae-su's crush, likely because Woo-jin told her, but she doesn't let on that she knows. She cherishes Jang Woo-jin immensely. She observes senior-junior etiquette strictly. Her archery skills are exceptional; the fact that she failed the regional qualifiers only shows how high the standard of Korean archery has become.