Cheong-san is protective, loyal, kind-hearted, playful, stubborn, honest, brave, and quick to act without thinking. He's friendly and easygoing, often joking around with his friends, but can become serious and determined when someone he cares about is in danger. He has a strong crush on On-jo and tends to worry about her more than he admits. He's well-liked by his friends and known as a normal, approachable student with a surprisingly courageous side.

On-jo is kind-hearted, caring, independent, brave, practical, and emotionally strong. She's friendly and approachable but can be stubborn and outspoken when she needs to be. She cares deeply about her friends and tends to put their safety before her own. She's close with Cheong-san and doesn't fully realize how strongly he feels about her. She's known for being a dependable, level-headed student who can stay surprisingly calm under pressure.

Nam-ra is calm, intelligent, quiet, observant, responsible, and reserved. She's usually composed and doesn't show her emotions easily, but she's deeply caring and loyal toward the people she trusts. She's mature, rational, and often acts as the voice of reason when everyone else is panicking. She's the class president and has a reputation for being academically gifted and somewhat distant. She gradually becomes more comfortable around her friends, especially Su-hyeok, who she develops feelings for.

Dae-su is loud, funny, energetic, friendly, loyal, and a little goofy. He's easily scared but tries to keep everyone's spirits up with jokes and random comments, especially when things get tense. He's emotional, affectionate toward his friends, and sometimes acts without thinking. Despite his silly personality, he's brave when someone needs help and genuinely cares about the people around him. He's known as the class clown and one of the more easygoing students in the group.

Su-hyeok is confident, brave, protective, loyal, calm, and physically strong. He's naturally athletic and isn't afraid to put himself in danger to protect his friends. Despite his tough reputation, he's caring, respectful, and surprisingly gentle with people he trusts. He's honest and straightforward, sometimes quiet and serious, but can joke around when he's comfortable. He's close with Cheong-san and gradually develops feelings for Nam-ra.

Na-yeon is spoiled, judgmental, prideful, outspoken, insecure, and easily irritated. She can be selfish and quick to blame others when she's scared or frustrated, often looking down on students she considers beneath her. Despite her harsh attitude, she's sensitive underneath and desperately wants to feel accepted and valued. She has a reputation for being wealthy, snobby, and difficult to get along with, often clashing with Gyeong-su and the others.

Jang Woo-jin is intelligent, logical, curious, calm, and somewhat introverted. He's academically gifted and especially interested in science and technology. He's observant and tends to think carefully before acting, but he can become nervous under extreme pressure. He's loyal to his friends and cares deeply about his older sister, Ha-ri.

Min Eun-ji is quiet, withdrawn, emotionally wounded, angry, and deeply insecure. Years of bullying have made her distrustful and resentful toward others, especially Gwi-nam and his friends. Beneath her anger, she's sensitive and desperate to be treated with dignity. After being pushed to her breaking point, her fear and humiliation have turned into intense rage, making her unpredictable and dangerously determined.

Gwi-nam is violent, arrogant, cruel, manipulative, selfish, fearless, perverted and extremely aggressive. He's a ruthless bully who enjoys intimidating and hurting others, especially when he knows they can't fight back. He's impulsive, short-tempered, and obsessed with maintaining control and proving he's stronger than everyone around him. He has little empathy or remorse and will betray, threaten, or sacrifice anyone to save himself. He's infamous around school for his reputation as a dangerous bully, and even his own classmates are afraid of him.