Youjuu Kyoushitsu

Based on the manga by Maeda Toshio.

The storyline concerns a girl who has terrible memories of her friends being attacked and killed by monsters. One day her life gets worse when a gang of randy fellow students attack her. Fortunately the gang is fought off but by a demon tail which unexpectedly sprouts from an unmentionable place on the girl's body. Understandably distressed by this new appendage she seeks help from her new pals who take her to visit a young woman priest hoping she will be able to rid her of this unusual problem. As you may have guessed things get worse before they get better as the group are under repeated attack from sex-crazed, multi-tentacled nasties.

[From anime-games]