Classmate wa Chijo Bakari!

Our protagonist is of the small, timid, and sickly sort. However, since he's just returned from the hospital with a clean bill of health, his teacher and classmates waste no time in jumping his bones. It would appear that many of the women in the classroom are desperate for a man, either out of lust or for experience for the future. Not like our hero minds - he has a soft spot for the fairer sex.