The official website of the 2nd part of the anime The Case Study of Vanitas ( Vanitas no Carte ) will have a total of 12 episodes.
According to OA debut from The Case Study of Vanitas ( Vanitas no Carte ) will take place on January 14, 2022 with animation is from Bones ( Boku no Hero ).
Synopsis:
Despised by others of his kind for being born under a blue moon, the vampire Vanitas was left fearful and desolate. According to legend, he created a cursed grimoire known as The Book of Vanitas, and it is said that he would one day use it to bring retribution to all the vampires of the red moon. In Paris in the 19th century, Noé Archiviste is in search of the legendary Book of Vanitas. While traveling aboard an airship, he is saved from a vampire attack by an eccentric doctor who calls himself Vanitas and carries the book he seeks. Ironically, the self-proclaimed vampire expert is a mere human who inherited his name and book from his master, the same Vanitas of legend. As strange cases arise, the doctor's ability to restore vampires to sanity proves to be very beneficial.
Finally the manga of The Case Study of Vanitas won a publication in December 2015 in Gangan Joker .
Source: Official website