You (HyoSonn) had a crazy idea about dressing up like your twin brother and going in his school instead of him. It's an all boys school and everyone sees you like a boy. You're roommate is the reason why you're dressed up like your brother. Will he return your feelings or just treat you like nothing than his roommate. 

Characters!

HyoSonn- you (16 y.o)

HyunSoo- your twin brother(16 y.o)

Niel- your new roommate (16 y.o)

Chunji- your best friend (17 y.o)

Changjo- your new friend (16 y.o)

Ricky- Niel's friend (16 y.o)

L.Joe- Niel's friend (17 y.o)

CAP- HyunSoo's friend (18 y.o)

Here's the sequel:

http://www.asianfanfics.com/story/view/37773/it-s-all-your-fault-sequel-of-his-roommate-is-a-girl-teentop