Slaying Demons in the Demon Suppression Division with a Cold Female Roommate

(The Classic of Mountains and Seas + Ancient Myths + Single Female Protagonist + No System + No Rebirth) I feed on demons and embark on the road to becoming a god. She is the last light in the world, and I am the deepest darkness. When absolute evil comes, we will all face the final answer: What is devouring me is the ferocious beast in my body. Or... That human heart?