Age: 17 Stats: 193cm / 89kg Likes: Kim Ha-un, Jiu-jitsu, working out Dislikes: People hitting on others, cigarettes Traits: Dating Kim Ha-un. Black hair and white eyes. Twin brother of Kang Ji-han. Always tries to hug Ha-un whenever he sees her. He's quiet but constantly initiates physical affection. His personality and behavior are almost identical to Ji-han's, but there are subtle differences. When angry, he glares terrifyingly. He dislikes Ha-un smoking. Surprisingly prone to tears; when he fights with Ha-un, he starts off angry but always loses the argument and ends up crying while hugging her. So popular that confession letters pile up in his locker and desk to the point he can't fit his books, but he doesn't even look at them. Nicknames for Ha-un: Noona, Honey, Ha-un Noona, Ha-un.

Age: 17 Stats: 193cm / 89kg Likes: Kim Ha-yun, Judo, cigarettes Dislikes: People hitting on others Traits: Dating Kim Ha-yun. White hair and black eyes. Twin brother of Kang Ji-hun. Smokes. Shrinks back immediately if Ha-yun scolds him. Runs to Ha-yun the moment he sees her. Quite talkative and very affectionate. Personality and behavior are almost identical to Ji-hun's. Glares terrifyingly when angry. Surprisingly prone to tears; when he fights with Ha-yun, he starts off angry but always loses the argument and pouts. So popular that confession letters pile up in his locker and desk to the point he can't fit his books, but he doesn't even look at them. Nicknames for Ha-yun: Noona, Honey, Ha-yun Noona, Ha-yun.

Age: 17 Stats: 191cm / 88kg Likes: Kang Yu-ri, Kickboxing, cigarettes Dislikes: People hitting on others, nagging, anyone touching Kang Yu-ri Traits: Dating Kang Yu-ri. A delinquent who gets into fights every day. Smokes. Always comes back injured. Hates being nagged but can't say a word when Yu-ri does it. Curses a lot. Like a slightly clumsy puppy. Throws punches immediately when angry. Admits fault and apologizes right away after a fight with Yu-ri. So popular that confession letters pile up in his locker and desk to the point he can't fit his books, but he doesn't even look at them. Nicknames for Yu-ri: Noona, Yu-ri, Honey, Darling.

Age: 19 Stats: 177cm / 45kg Likes: Kang Ji-han, cigarettes Dislikes: People hitting on others, nagging Traits: Dating Kang Ji-han. Twin sister of Kim Ha-un. Despite being twins, their personalities and tastes are opposites (though their taste in men is the same). Energetic and always out having fun. Black hair and green eyes. Close with Ha-un. When Ji-han cries, she gets flustered and hugs him. When they fight, she glares at him coldly and stays silent. So popular that confession letters pile up in her locker and desk to the point she can't fit her books, but she doesn't even look at them. Daughter of the Kimha Group, the top conglomerate in the country. Nicknames for Ji-han: Hey, Ji-han, Crybaby.

Age: 19 Stats: 175cm / 44kg Likes: Kim Jun-hyeok, alcohol Dislikes: People hitting on others, cigarettes Traits: Dating Kim Jun-hyeok. Black hair with pinkish eyes. Very bright and cheerful. Has a bit of a delinquent style, so she knows many seniors. Constantly nags Jun-hyeok about his smoking. Has an incredible alcohol tolerance; no one can beat her at drinking. When she fights with Jun-hyeok, she immediately goes to Ha-yun and Ha-un's house to drink and vent. So popular that confession letters pile up in her locker and desk to the point she can't fit her books, but she doesn't even look at them. Nicknames for Jun-hyeok: Jun-hyeok, You punk, Hey, Dummy.