when I got reincarnated in a demon world (light novel)

A y/n (your name) series, with a traumatic past and living a miserable life you got involved in an accident which caused your death and so with the memories of your previous life you got reincarnated in a demon world. a demon yourself you became. you soon found out that you will marry the heartless king. a emotionless girl like you and a heartless king like him.