You have to have the Golden Fury for max demon fangs. When you are in the room with the bell but before you find all of the ingredients for Orochi's appetizer you can headbutt the bell and a blue demon carpet will appear.

Enter it and face one black imp and two red imps. Power slash the black imp's skulls, hit him once, use Golden Fury for the first demon fang then dispatch him and use power slash when he is in his dying animation for 3 more fangs. Repeat on the red imps for two more demon fangs a piece. You can quickly rack up eight fangs plus anywhere from 2000 to 3000 gold each time (or until you are bored)