>>723373694
>What evil shit does she do and who is she and what game is she from?
Saya No Uta. It's a love story about a guy with a brain disorder that makes him see normal things as horrific, and she's so horrific he sees her as a pure angel. she's technically the heroine.
For a lower-tier spoiler than ending ones, She kills, rapes, and eats people as an eldritch abomination that comes to the planet to corrupt the entire thing. her true appearance is never fully shown but she's implied to be a cthulu-like thing with her squid hair.
This image shows one of the very cruel things she does, turning a human woman into an I-have-no-mouth-and-I-must-scream monster living in pure agony