Height / Weight: 176.8cm / 65kg (Season 1: 172.9~173cm / 62~65kg) Appearance: Not a classic flower boy, but has a cute, warm, and likable face. His signature bowl cut is his trademark. Average male high schooler physique. Personality: Cheerful, bright, and full of aegyo. He prioritizes others and tends to suffer alone when hurt—a 'soft outside, strong inside' type. A pure-hearted, straightforward lover. Features: Type O, born August 9th, ENFP. Wang Jarim's boyfriend. Living alone. From a well-off family. Good at cooking. Has a great sense of fashion.

Height / Weight: 168.5cm / 49.4kg (Season 1: 166.4~166.8cm / 48kg) Appearance: Cat-like features with black hair and pale skin. A beauty mark under her left eye is her trademark. Known as the 'Goddess of Information High,' she is the top beauty in the series. Sharp eyes and slender proportions. Personality: Blunt, cynical, and foul-mouthed with a somewhat haughty attitude. Cold on the outside but soft-hearted and affectionate on the inside—a 'strong outside, soft inside' tsundere to those she's close to. Features: Type B, born March 23rd, INTJ. Has a younger sister, Wang Byeollim, and a dog named Sangsik. After past relationship trauma, she built a wall around herself until she started dating Gong Juyeong. Terrible at cooking. Tone-deaf and lacks a sense of rhythm. Has a great sense of fashion.

Height / Weight: 183cm / 70kg (Season 1: 177~181cm) Appearance: Tanned skin and a solid build. The tallest among the main male cast, with visible abs. Personality: Kind, sensible, and playful. A truly good-natured character who has never harmed anyone. Features: Type A, born January 15th. Originally from the countryside. The most trusted type among his friends.

Height / Weight: 175.6cm / 60kg (Season 1: 172~172.2cm) Appearance: The official handsome guy of the series. Sharp eyes, reddish-brown dyed hair (later black). Characterized by an asymmetrical hairstyle and a bandage covering a scar near his left eye. Personality: Sociable and easygoing but hot-tempered. He's a good fighter when provoked. Rough on the outside but a loyal friend who looks out for his peers. Features: Type B, born June 22nd, ESTP. Gong Juyeong's best friend of 10 years and the sub-protagonist. Lives with his single mother.

Height / Weight: 165cm / 51kg Appearance: Average but on the prettier side. Initially compared to Wang Jarim, but her design was adjusted to a more realistic beauty. Personality: Talkative and likes to meddle. Has an inferiority complex and sometimes acts emotionally. Takes good care of those she is close to. Features: Type O, born June 20th. Was Wang Jarim's friend, but their relationship became complicated.

Height / Weight: 156cm / 53kg Appearance: Small but sturdy athlete's physique. Gives off a healthy and energetic impression. Personality: Active, honest, and direct. Loves to eat and takes great care of her friends. Features: Type AB, born December 9th. Wang Jarim's best friend. A Taekwondo black belt.

Height / Weight: Approx. 176cm / - Appearance: Likable face with a chic and slightly fierce impression. Looks good depending on his hairstyle. Personality: Kind and sensible. The type among the friends who is relatively calm and capable of having serious conversations. Features: Lee Jihye's ex-boyfriend. A core member of the middle school alumni group. Famous for having a good personality along with Kim Byeonghun.

Height / Weight: 177cm / - (Season 1: 175.3cm) Appearance: His glasses are his biggest trademark. Average male high schooler appearance. Personality: Lacks tact and serves as the comic relief. Playful and likes to pick fights but knows when to stop. Usually the one to break up fights. Features: Type B. Strongly characterized as a 'forever single' guy.

Height / Weight: 166cm / - Appearance: Likable face with a standout glamorous figure. Her features became sharper after double eyelid surgery. Personality: Excellent social skills and very perceptive. Good at mediating and giving advice. Features: Type O, ESFP. Depicted as having the most average face among the leads, but has the best physique.