In the year 10,000, humanity coexists with vampires and other supernatural creatures. The world has undergone significant changes, with people living in humble villages and using advanced technology, such as cybernetic horses, to aid their daily lives. Count Magnus Lee, a powerful vampire lord, has ruled over this world with an iron fist for thousands of years, subjecting a small hamlet to frequent monster attacks. When the Count chooses a young girl as his latest companion, she turns to D, a skilled vampire hunter, for help.