Amber enters the all-boys school ,Seoul Boys School of Performing Arts (SBSPA), because the sister school, Seoul Girls School of Performing Arts (SGSPA), mistook her for a boy when they saw her ID photo. So they re-enrolled her into SBSPA. Then by the time she found out it was too late to get back into SGSPA. So she has to pretend to be a boy to enter the school. She encounters many obstacles and experiences the things she would never experience if she was not pretending to be a guy. 

Amber 
A girl that looks like a boy. Amber and Key become best friends. She is studying rapping, dancing and singing.

Jonghyun
Amber's twin brother (They really do look the same in real life) in the most popular group in school. He is studying singing and dancing.

Sulli
A cute and outgoing girl. Best friends with Taemin. Victoria’s younger sister. In the most popular group in SGSPA the cute one of the group. She is studying singing and dancing.

Taemin
Taemin is a quiet and shy boy. Best friends with Sulli. He doesn’t like to show his talents to people. He is studying singing and dancing.

Victoria
Sulli's sister. In the most popular group in SGSPA the leader of the group. She is one of SGSPA's best dancers. She is studying Singing and dancing.

Nichkhun
Jonghyun's best friend. In the most popular group in school the face of the group. He is studying rapper and Singer, Dancer

Minho
Straight forward guy. In the most popular group in school he is the leader of the group. He is studying rapping.

Key
A Diva like guy. In the most popular group in school he is the fashionistar of the group. He is studying Vocals, Rapper and Dance

Onew
Kind, loving, adorable boy he can never be hated ;) In the most popular group in school a fatherly person. He is studying singing and dancing.

Luna
A very quiet, cute and lovable girl. She is in the most popular group in school.  Studying singing and dancing

Krystal
A very persistent girl, she tries to get everything she wants with any possible method; she is very nosy and is two-faced. She is studying singing and dancing.