Before humans ruled this world, vampires once ruled this planet. Among them, the most glorious golden age was composed of three countries: the Nofelus Empire, the Asamatha Empire, and the Cappadosi Empire. Vampires, humans, and hybrids of vampires and humans make up the residents of each country, but their identities are not equal. Vampires are mainly nobles, hybrids are mainly civilians, and humans are slaves living in the gap between the two.