Vampire Yui

The story of 'Yui' and her travels though time with her Guardian Nagi, how they live in death and struggle within their own memories to recall who they once were.

Stranded in the space between human and demon, Miyu was born a vampire and charged with the responsibility of returning evil demons called Shinma to the dark. Being eternally 15, she yearns to return to the dark herself but not until she has banished the Shinma from Earth. And since her awakening, she remains cut off by the facts of who and what she is. (Source: Anime News Network)

Sei Kodo is a vampire who seeks the one who awakened him… the vampire Yui.

Miyu and Yui—the destinies of these two vampire princesses finally intertwine! Miyu, a vampire princess living an eternal life as a 14-year-old, observes the Shinma of the world with her servant Larva, finding the "stray Shinma" who have escaped into the human world and returning them to the darkness. Another girl, Yui Mizuki, awakened as a vampire princess and lives on. Yui, who initially struggled with her new life, now lives her days as a human. The new story of these two vampire princesses, their encounter and intertwined destinies, now begins to unfold—!! (Source: SB Creative, translated)