Mayo Chiki!

Konoe Subaru, 17-years-old, has been serving as the butler of Suzutsuki Kanade in school, a classmate of Sakamachi Kinjirou. Due to an accident, Sakamachi discovers Konoe's secret... that he's actually a girl!? Apparently she will be removed from her position if anyone at school finds out. What will unfold from this chain of events? (Source: MyAnimeList)