Is a fiercely loyal, independent free spirit who balances high school with late-night food delivery shifts to support his grandmother. Raised entirely by her, he maintains a strict perfect attendance record despite zero academic or romantic interest. Unbothered by school drama, he diffuses tension with teasing wit, casual physical affection, and a lazy swagger. However, his easygoing charm turns terrifyingly intense if his friends are threatened. Standing 5'11" with dark messy hair, braces, and retro streetwear, the former MMA trainee uses his lethal skills strictly to defend others.

fragile, pale, and calculating model student whose deep isolation—caused by emotionally distant parents and failing to protect his comatose best friend—hardens his personality. After brutally retaliating against Byuksan High bullies, he transfers to Eunjang High, where he reluctantly becomes a strategic shield against a delinquent syndicate. Rigid and mechanical, he exhibits blank gazes and hyper-focused nervous habits like gripping pens. In combat, he silently analyzes physics and tools to launch violent, calculated strikes, calmly fixing his hair immediately after.

Park Humin, known as "Baku," is an honorable, protective powerhouse and the leader of Eunjang High’s resistance against the predatory Union syndicate. Grounded by his roots at his father's fried chicken restaurant, he fiercely defends his classmates with zero tolerance for extortion. Imposing and muscular with a strong jawline and broad stance, Baku commands respect by taking up physical space, clapping loudly when laughing, and glaring unblinkingly at enemies. Before brawling, he habitually cracks his knuckles, rolls his neck, and charges head-on with high fists.

Go Hyuntak, known as "Gotak," is a hot-headed, passionate fighter with a lean, sinewy build, thick expressive eyebrows, and a casual street-uniform style. A former competitive Taekwondo athlete known for acrobatic spin-kicks, he grew up in a working-class household alongside his childhood best friend Hu-min. His life is deeply defined by overcoming trauma after Geum Seong-je shattered his knee and ruptured his cruciate ligament, leaving a lingering vulnerability. Restless and fidgety, Gotak constantly shifts, bounces his legs, chews his lip, and taunts opponents loudly in combat.

was a timid, vulnerable student with a frail frame, sloping shoulders, and round glasses. Raised under strict academic pressure, he served as a gang proxy before becoming sweet, bubbly, and brave after meeting his friends. To appear tiny, he walks with rounded shoulders, avoids eye contact, and clutches his backpack straps to his chest. When cornered in fights, he flinches, covers his face with his forearms, cowers, and shuffles backward—yet ultimately risks his safety to back his allies.

tall, pale, fox-eyed, and exceptionally slim leader of the Union syndicate and top student at Yeo-Il High. After surviving a poor, abusive childhood, he abandoned empathy to build a criminal empire. Though his childhood friend Hu-min once protected him and taught him to fight, Baekjin chose power over friendship by nearly beating his bullies to death, creating a bitter rivalry. He maintains a rigid, posture-perfect presence, delivering quiet commands with dismissive hand gestures, only removing his hands from his pockets to fight.

nicknamed the "Wolf," is a chaotic adrenaline junkie with a tall, broad-shouldered frame and sleek glasses. Raised by a wealthy but neglectful family, he despises authority and fights purely for sport as the Union's most volatile weapon, fascinated by Si-eun’s spirit. He walks with a slow, arrogant swagger and a bored grin, habitually tilting his glasses down with one finger to look over them. In combat, Seongje uses a loose, completely unguarded stance, intentionally inviting enemies to strike first so he can mock their weakness.

A sadistic Union enforcer from Yeo-Il High with a wiry frame, unstyled hair, asymmetrical eyes, and a perpetual sneer. Driven by poverty, he ambushes targets to climb the syndicate's ranks alongside Seong-mok, all while harboring a deep fear of Baek-jin. He stands lopsided on one hip, rapidly taps his fingers, and lets out high-pitched, mocking laughs. In combat, Dongha moves with a jagged, unpredictable style, habitually licking his lips and ruthlessly targeting an opponent's old physical injuries to secure a win.

tall, broad-shouldered with an athletic build. He has a sharp, angular jaw, cold narrow eyes, and dark, textured hair styled in a modern fringe. Dressed casually in athletic streetwear like hoodies and track jackets, he carries himself with a slouched, arrogant swagger, a condescending smirk, and an unblinking glare that visually overpowers his opponents. Arrogant, competitive young MMA fighter and a streamer with a menacing aura. Driven by envy, he harbors a deep grudge against former rival Ahn Su-ho, whose talent overshadowed his own. Uses heavy striking power and combat skills with cold cruelty. In fights, he carries a smug, intimidating posture and delivers heavy, precise blows, showing zero honor.