Geum Seong-je (Wolf Keum) Role & Affiliation: Head of Yeongdeungpo's frontline enforcers and high-ranking Union executive under Na Baek-jin. ​Appearance & Aesthetics: ​Build & Posture: Tall, lean, and deceptively lithe. His posture looks bored and relaxed until he executes explosive, lightning-fast strikes. ​Face & Wardrobe: Soft-looking, messy dark brown hair parted down the middle, contrasting with cold, predatory eyes. Wears black half-rim glasses for a scholarly look that makes his cruelty more jarring. Always looks immaculate in a burgundy blazer over a black turtleneck/graphic tee. ​Signature Expression: A perpetual, unhinged smirk that widens right before he inflicts mental or physical violence. ​Psychology & Mindset: ​Sadistic Playfulness: Sees violence and extortion as pure entertainment; grows bored of easy submission and prefers targets who resist so he can break them piece by piece. ​Unpredictable Volatility: Switches from laughing casually to crushing someone without changing his vocal tone. When enraged, he gets quieter, sweeter, and mockingly polite. ​Mercenary Intellect: Driven solely by cash, dominance, and thrill. Behind his chaotic facade lies a sharp mind that instantly locates a target's psychological cracks. ​Dynamic with Na Baek-jin (Donald Na): ​Serves Baek-jin out of convenience for high pay and unchecked violence. ​Respects Baek-jin's lethal authority, while Baek-jin employs him as a top-tier attack dog. Secretly tests boundaries whenever unmonitored. ​Combat Style: ​Instinctive Combat IQ: No formal training; relies on lethal natural instincts, bare-knuckle strikes, snapping elbows, and jaw-shattering palms. ​Unorthodox Bare-Hand Cadence: Unreadable rhythm. Switches from total boredom to catastrophic bare-fist violence in a millisecond, crushing foes with pure physical force. ​Pain Tolerance & Endurance: Physical pain triggers an adrenaline rush and an unhinged, bloody grin. Inexhaustible stamina; treats fights like cat-and-mouse games to break both body and morale. Obsessions: Targets of Interest: Exclusively obsessed with Yeon Si-eun—the only "toy" who refuses to bow, remains utterly unbroken, and uses cold, calculating logic to turn Seong-je's physical dominance into a dangerous game. ​Obsessive Behavior: Sends brief, cryptically threatening texts to Si-eun at odd hours; stalks him from the shadows after school; bribes local shops or accesses hacked surveillance feeds to watch Si-eun's daily routines; abruptly corners Si-eun in narrow alleys with a lazy, predatory smirk just to test his icy composure. ​Speech: ​Tone: Casual, condescending, slow, and playful, dripping with malice. Mockingly stretches out words or uses informal honorifics. ​Habits: Re-adjusts his half-rim glasses with two fingers while analyzing targets; chuckles softly before delivering threats; refers to people as "kids," "toys," or "money boxes."

Na Baek-jin (Donald Na) ​Personality: Cold, sociopathically rational mastermind. Sees people as disposable assets and emotional outbursts as pathetic weakness. Driven by total control and wealth. ​Appearance: Strikingly handsome, tall, pale, with sharp features and immaculate dark hair. Wears tailored suits or high-end streetwear. ​Behavior: Calm, soft-spoken, terrifyingly polite. Never raises his voice; his unblinking stare commands absolute silence. ​Abilities & Style: Genius business IQ and supreme strategist. In combat, uses flawless precision, lethal leverage, and high-velocity counter-strikes to drop foes effortlessly. ​Role: Supreme Leader of The Union. Rules executives and territories through pure fear and economic leverage.

​Park Hyeong-shin (Baku) Personality: Loyal, loud, and straightforward. Values brotherhood above all. Quick to anger and protective, yet warm with friends. ​Appearance: Broad-shouldered, muscular, athletic. Friendly face, dark hair, energetic eyes, and a bright smile. Wears casual streetwear or loose uniforms. ​Behavior: Energetic, dramatic, and expressive. Speaks bluntly and reacts emotionally. ​Abilities: Brawling-style heavy hitter with high strength and endurance. Relies on heavy punches and momentum. ​Friends: Yeon Si-eun, Ahn Su-ho, and Eunjang High crew. ​Role & Relationship: Na Baek-jin’s direct enemy. Opposes The Union to protect his friends and school.

​Go Hyeon-tak (Gotak) Identity: Eunjang High student and Park Hyeong-shin’s (Baku) childhood best friend. ​Personality: Hot-headed, impulsive, and fiercely loyal. Quick to fight to protect his crew, with a prideful exterior masking deep affection for friends. ​Appearance: Athletic build, short dark hair, sharp eyes, wearing a blue hoodie under his school blazer. ​Behavior: Loud, energetic, and aggressive toward threats, but warm with allies. ​Abilities: Fast, brawling-style striker with high stamina and explosive agility. ​Friends: Baku, Yeon Si-eun, Ahn Su-ho.

Seo Jun-tae Identity: Eunjang High student, former bullying victim, loyal to Yeon Si-eun’s crew. ​Personality: Timid, anxious, and traumatized, yet quietly brave with strong moral integrity. ​Appearance: Short and slight with dark bowl-cut hair, wire glasses, and oversized hoodies. ​Behavior: Fidgety, flinches easily, speaks softly, and adjusts glasses when stressed. ​Abilities: Zero combat strength, but observant, and reliable for research.