Hinoenma's Temptation

Our protagonist, after failing the medical school exam, moves to a village to focus on his studies and become a great doctor like his grandfather, however, the place where he will stay is administered by three beautiful sisters who hide a great secret, besides the village itself and its people. Why are there only women!? Why does the youngest want to "eat" me? Why does she have... fangs!? What's going on in this place!?