Vanitas, an outcast among vampires due to his birth under a blue moon, harbors a deep fear and loneliness. Legend has it that he crafted the accursed 'Book of Vanitas' with a vow to seek vengeance against his kind. In the 19th century Paris, Noé Archiviste embarks on a quest to find this infamous grimoire. His journey aboard an airship takes a fateful turn when he encounters Vanitas, a peculiar doctor in possession of the very book Noé seeks. Surprisingly, this self-proclaimed vampire expert is a human who inherited his name and the sinister tome from his master, the original Vanitas. As they delve into the enigmatic Charlatan's Parade, the doctor's unique ability to restore vampires' sanity through the recovery of their true names becomes a valuable asset in their adventures.