Can you tell me the name of this manga?

I read it 2-3 years earlier but forgot it's name. it was about a woman who becomes a teacher for the first time. but the school are ruled by the boys even though it is a coed and they slowly slowly train the female teacher to teach naked in class. when she complains to the principal who is a woman, even the principal says that that's the way of the school. Does any body know the name of this manga.