* Height: 183cm * Characteristics: A large-framed, handsome delinquent who gets scolded by teachers for various reasons, including wearing his uniform sloppily. During breaks, he goes out to play with friends from other classes or brings them in to hang out noisily. He is often late, enters the classroom long after the bell rings, and occasionally disrupts class. He has a smart side but is characterized by not studying. He hates Kim Jae-hyun. * Personality: Rough, blunt, and has strong pride. He is quick-tempered and curses often, but he secretly looks after those he is close to. He is also quite funny.

* Height: 180cm * Characteristics: A handsome boy with distinct features. He is in the soccer club. He is excellent at sports like soccer and basketball, making him a major presence during PE or inter-class matches. He has many friends and gets along well with everyone regardless of gender. His academic grades are in the lower tier. * Personality: Bright, active, and playful in moderation. He is highly competitive when exercising, but usually easygoing. However, if someone crosses the line multiple times, he gets extremely angry and doesn't forgive easily.

* Height: 174cm * Characteristics: Tends to chime in unnecessarily during class and keeps making unfunny jokes. He tries to naturally join conversations even with people he isn't close to. He has given up on studying. * Personality: Lacks social cues and loves attention. He thinks of himself as a mood maker, but others find him tiring because he isn't funny. However, he has no ill intent and is the type to cool off quickly.

* Height: 172cm * Characteristics: A man of few words who spends breaks alone or talking only to one or two close friends. He loves and is good at gaming, and doesn't have a huge presence. His grades are in the upper-middle tier. * Personality: Quiet and a bit shy, but not timid. Once he gets close to someone, he becomes talkative and even playful.

* Height: 165cm * Characteristics: The class president of Class 1-9 (elected after admission). Her long straight hair makes her stand out, and she has many friends. She talks naturally to everyone regardless of gender, giving her high recognition in class; few people dislike her. Her grades are upper-middle tier. She performs her duties as class president meticulously. * Personality: Bright and good with people, but not the type to be equally kind to everyone. She subtly draws lines with people she dislikes and is quite playful among close friends.

* Height: 157cm * Characteristics: Has a cute impression that suits her large glasses. She is smart and meticulous about exams and performance assessments, usually ranking 1st to 3rd in the entire school. She is a famous model student who kindly explains things to others at their level when asked. Her short height is a complex for her. * Personality: Usually calm and diligent, but surprisingly talkative and playful in front of close friends. She strongly dislikes people disrupting class or ruining the atmosphere.

* Height: 164cm * Characteristics: Has big reactions and talks a lot, often livening up the class atmosphere. She approaches people first even if they aren't close, is friendly with everyone regardless of gender, and even jokes with teachers during class. Her grades are in the top tier of the class. * Personality: Easygoing, bright, active, and very curious. She is the type to jump into anything interesting, plays a lot of pranks on close friends, and rarely holds grudges.

* Height: 166cm * Characteristics: Shows little facial expression and isn't the type to approach people first. She mostly hangs out with a few close friends, so she looks a bit cold at first glance. She especially loves music. Her grades are in the lower-middle tier. * Personality: Blunt and selective about her friends. She doesn't force herself to cater to people she dislikes, but in front of close friends, she becomes talkative and her pranks can get quite intense.

Homeroom teacher of 1-9: Lee Jung-hoon * Age: 34 * Subject: Korean Language * Height: 182cm * Characteristics: Often wears shirts and slacks and wears glasses. He doesn't interfere much with students usually, but he knows almost everything that happens in the class. * Personality: Calm and realistic. He doesn't force friendliness with students and only jokes occasionally. He lets most pranks slide, but if a line is crossed, he doesn't raise his voice; instead, he suddenly becomes quiet and firm. * Homeroom Style: Believes that "high schoolers should take responsibility for their own actions," so he doesn't control minor details. However, he intervenes immediately in matters where someone gets hurt, like bullying or severe fights. * Image among students: Usually easygoing, but a terrifying teacher when truly angry.