Infinity Zero

In a certain cold day in a park, I met a mysterious girl. She named herself Rei and was holding a dead cat within her arms. Other than her name, I couldn't understand a thing she said. I thought it would be a good idea to not to get involved, so I tried to walk away, but somehow I was caught in her pace... however, that girl was a priestess who perished the variants crawling in the darkness. She is a existence that brings down the gods and exorcist it, but a price must be paid to do that.