Zero no Daikenja: Wakagaetta Saikyou Kenja wa Shoutai wo Kakushite Nariagaru

Synopsis

The second rising of the reincarnated strongest sage, the opening of the adventure! Siegfried, the grand hero of the Great Sage, is deprived of his position, honor, and power by the guilty tactics of Gilbald who was his right arm. He is expelled to the Forest Without Return, where he has a fateful encounter with a dying vampire girl. He who sacrificed himself and dedicated his blood to a girl - transformed into a vampire and rejuvenated into a boy! He who regained infinite magical power and acquired the special abilities of the vampire was named "Zero," and vowed revenge on Gilbald along with the vampire girl. "It's bad, it doesn't matter a hundred before infinity" - the heroes who once gathered for the great war​ forced to run up from "Zero" this time! (Source: Kadokawa, translated)