Wooyoung was always shy growing up but when he meets I'm Ji Nah, his dream girl, they start dating and he changes himself to become someone she wants him to be. Confident, stylish and desired.

His world revolves around her so when she breaks up with without a reason, turning his world upside down he enlists the help of his sister Gahee, her boyfriend Junsu and friends Nichkhun and Junho to get into the same co-ed boarding school as her, disguised as a girl so he can win her back. There he meets a cute, lively girl named Bae Sue Ji and gets roomed with Kim Yu Jin, a bright and beautiful girl who befriends the female version of him and starts working her way into his heart. How will they change each other? What will happen when his time as a girl starts running out? What will Yu Jin do if the friend she loves and cherishes as a girl is revealed to be a boy?