Vanitas, a vampire born during a rare blue moon, suffered from rejection and isolation among his own kind. Determined to exact vengeance, he created a cursed grimoire called the "Book of Vanitas," with the intention of using it against all vampires of the red moon. In 19th century Paris, Noé Archiviste embarks on a quest to find the elusive Book of Vanitas. While travelling on an airship, he is rescued from a vampire attack by the peculiar Doctor Vanitas. To Noé's amazement, the doctor possesses the very volume he is seeking and declares himself to be a specialist in vampire lore. However, it soon becomes clear that the doctor is not a vampire himself but a human who inherited both the book and the legendary name from his mentor, Vanitas. The doctor's ability to restore vampires to sanity by discovering their true name proves invaluable as they investigate the mysterious Charlatan's Parade.