Hi^^
I'm looking for a shoujo or josei manga with this plot:

The main girl character is in love with her male best friend,but she didn't confess, the time pass
and they are in high school, on first school day she met a veryyyyy cute girl who is very close to her
loved one, and she get jealous.
I really don't remenber what happen next, just the part that she find the cute girl is a boy, a very pervert boy xD

Could someone help me find this manga name?

*sorry for any grammar mistakes, english isn't my first language

Thanks!!!