Injû kyôshi II - jissha-ban

This slice of shot-on-video hentai horror kicks off with a crazy old woman stealing what looks like all-butter shortbread from three statues wearing red hats. This causes an earthquake which releases ancient demon spores from a cave into a nearby pool of water. Unfortunately, this pool is precisely where a lesbian professor—part of a group of students and teachers who are spending a few days camping in the woods—decides to refill her water canteen. She accidentally ingests the spores, which causes the eruption of huge, thrashing, veiny, slime-covered tentacles that seek out new victims and enter the nearest orifice, thus allowing the demon to pass from host to host.