Kozue is a demon of about 2000 years old, she decided to live in the human world because hell bored her, she lives alone in her apartment, even though she is a demon, she does not bother to hide her identity from humans , she considers herself as a modern devil, even though she lives in the human world, she continues to do evil among humans because of her demonic nature, she never knew love or could never experience it, she is not an easy woman.