At the beginning of the 21st century, more than half of the human race died and civilization retreated due to the global flood called " Tempest ". Around that time, the existence of "vampires" was confirmed along with humans. However, not everyone can become a vampire, and those who inherit the blood of Faust, the progenitor of vampires, do not become vampires, and some even become beasts and die. Good vampires are given new names, and the rest are collectively called "rezas." On the other hand, the vampires begin their journey in search of why they were born, in search of the meaning behind it, and in search of the "mother" who is called the vampire's hope.