Onegai, Nugashite.

There is a curse on this school. It prevents the person who commits "impure acts" from taking off his or her panties. Only the right hand of the protagonist can break the curse and remove the panties, his name is Kamite.

Kamite tells the girls that they have been cursed and that he can take off their panties, but... obviously it is almost unacceptable for them to have any man take them off...!

This is how the girls end up in a lot of trouble. But if the panties are not removed, they can get into even more trouble...