Aku Chuunyuu -Kimi ni Sasageru Akui no Tamashii-

Main character watches a meteorite fall at night and walks to the collapse spot. But he only finds a gothic girl Lilim at that place. Lilim says that she is a devil who arrives to the human world to become a full-fledged person. Protagonist can't help the temptation to teach her the obscene side of humanity. But the story takes an unexpected turn as the wings of destiny approach.

[From vndbreview]