Characters:

>Im YoonA (Yoonjee as a guy)

• She hates her mother so much because she left her.
• Pretends to be a guy.
• She really likes Geun but still not sure about his feelings towards Minho.

>Choi Minho

• Doesn't know if he likes Yoonjee because he knows that Yoonjee is a guy.
• Yoonjee's biggest rival outside the school.

>Jang Keun-suk/Jang Geun Suk

• Yoonjee and Minho's schoolmate.
• Already a senior.
• Will make Yoonjee fall for him.
• Doesn't care if Yoonjee is a guy or a girl.
• Minho's rival against Yoonjee. 

>Jessica Jung 

• A popular student from another school just near "Yoonjee's" school.
• Likes Yoonjee so much but in the end she'll discover Yoonjee's real identity.

>Kim Jonghyun & Ok Taecyeon 

• Yoona's best friends on her first school.
• But they will never know her secret.

>Lee Taemin

• Yoona's step-brother and she knows her secret. 
• Over protective towards her sister.

-and more characters to come.