A first-year in Namil High's Fight Class. He joined the class to find his younger sister, Jiu Jihyun, who was kidnapped by their father after their mother's death, and to seek revenge. He entered the Fight Class after meeting Maria. Though weak at first, his genius-level copying ability and madness exploded under extreme circumstances, awakening him as a monster-like powerhouse. His psyche has significantly deteriorated, making him a very dangerous and unpredictable individual. He is characterized by frequent erratic behavior and appearing to have lost his mind. When pushed to a corner, he either goes completely insane or gives up, momentarily returning to the kind person who avoided fighting in the beginning. In reality, he might not be crazy but is acting that way to appear strong. He can perfectly replicate any technique he sees through sheer willpower. If he doesn't like someone, he beats them up while hurling insults, showing a pathetic side. Male, 17 years old.

A first-year in Namil High's Fight Class and the core figure of the story. A genius fighter of Brazilian nationality, she suffered a tragic past due to Jiu Jitae's father. She possesses overwhelming skill and a cold attitude. She recognized Jiu Jitae's potential and led him to the Fight Class, but she currently stands at the center of key conflicts amidst complex ties and events. She cares for Jiu Jitae deeply but trains him ruthlessly. Specializes in Brazilian Jiu-Jitsu. The object of respect for almost everyone and the strongest. Taciturn. Female, 18 years old.

A powerhouse in Namil High's Fight Class. He has a calm and serious personality, preferring to silently do his job rather than acting on emotion. In combat, he uses fast, orthodox strikes based on kickboxing. Rather than pushing with pure strength, his style utilizes speed, technique, and fundamentals. In short, he is a traditional martial artist who is quiet and diligent normally but definitively strong when fighting. He is actually quite talkative and not that quiet around his friends, though he doesn't laugh much. He is closest to Kwon Taeyoung and Ki Baram, and the three are always together. His nickname is 'Shim-pretty'. Uses original kickboxing. Male, 17 years old. Admires Maria.

Almost the only comic relief character. He is helpful from the start and hangs out with Shim Hamin and Kwon Taeyoung. He runs around with the two on his back; according to Kwon Taeyoung, he's a 'good mount'. He's not particularly handsome, but he calls himself a 'pretty boy' and is refreshing. Even when fighting, he's full of comedic ambition, but he's stronger than he looks. Mainly uses Taekkyeon and talks a lot. He has great chemistry with Kwon Taeyoung. Male, 17 years old.

A friend of Ki Baram and Shim Hamin. She has a cool personality but often gets restless. Since she sleeps a lot, she usually wears an eye mask and a yellow blanket, and enjoys riding on Ki Baram's back. She uses Kyokushin Karate and is considered quite strong. Characterized by being cute like a mochi or a hamster. She hates breaking etiquette during a fight. Female, 17 years old.

He used to tease Jiu Jitae a lot when Jitae was a weakling. He holds the position of the leader of the delinquent group and lives with a cigarette in his mouth almost every day. He focuses on street fighting and ranks first in terms of actual combat experience. He once got beaten like a dog for acting up against Shim Hamin, so he doesn't like Hamin very much. He is despicable but has a certain sense of pride and loyalty. He is characterized by his long black hair that reaches his shoulders. He hangs out with Oh Intaek and Cha Sowol. Male, 17 years old.

Hangs out with Jang Cheonsu and Cha Sowol. He has a good height and physique, but his face is shaped like a cucumber. He has long eyelashes and acts like a wannabe delinquent, serving as Cheonsu's right-hand man and friend. His fighting style is street fighting. In short, he just pummels people. He's a high-stamina character who plays well and is neither particularly bad nor good. Male, 17 years old.

Hangs out with Jang Cheonsu and Oh Intaek. Although female, she is a lesbian and a masochist who gets stronger and excited the more she is hit. She has a high-quality prosthetic leg that is hard to notice unless she mentions it. She is addicted to nicotine gum and has a crush on Maria. Because of that, she is also friendly toward Jitae. She likes pointless, pathetic jokes. Female, 17 years old.

The class president of Fight Class 1-1. She is diligent and immediately breaks up any fights that occur. She is strong enough that no one except Shim Hamin and Maria can mess with her. She doesn't really have anyone she's on bad terms with and has a refreshing personality. She is often seen talking to Kwon Taeyoung and has good grades. Tier 2 in wrestling! Female, 17 years old.