"Vanitas" is a term that refers to a work of art associated with the transience of life; the trademark of such a work is to contrast symbols of wealth and prosperity with symbols of death. A fitting title for a vampire story protagonist.
Yuki Kajiura has been an avid reader of the manga since its debut in 2015. Fittingly enough she also composed for PandoraHearts (2009), another work by Jun Mochizuki.
Based on a fantasy shounen manga written and illustrated by Jun Mochizuki. It has been serialized in Square Enix's Shounen manga magazine Monthly Gangan Joker since December 2015.