Asa made Jugyou Chu!

Kakinozaki Ayana-sensei and student Kagami Yuuki move into a room in the girls dormitory for the new (co-ed) high school semester, requested by Ayana-sensei and approved by the schools' principal.
As one would guess, no one can find out he's living there so other than school classes, he has to cross-dress or else he'll be kicked out of school and dorm.