In a world, alongside humans, there exists a species that resembles them. They are known as 'cats'. In this world, humans carry the responsibilities of providing manual labor and sexual services. Cats experience periods known as 'heat cycles'. Unlike female cats, the male cats, who can enter countless heat periods utilize human males as their primary source of relief and medications to help suppress the influence of these heat periods. In a certain country, in a world known as this one…a cursed little black cat who lived in a big, big mansion picked up a strange man off the street.