Revive is a story with dark themes, hopeful protagonists, and a bloody past. Humans live in what is known by all the other races of the universe as Dimension-1, and are relatively aware of the existence of mages, a powerful race that resides in Dimension-2. Mindless creatures known as Relentless roam through the dimensions and are hunted by specially trained mages known as assassins. The main plot of the story revolves around 18-year old Yuuki Matsuzawa, a seemingly normal mage just graduated from high school and unwilling to explore his abilities to remain "human-like." Encountering Relentless and other creatures of the dark constantly has become normal for him, but a sudden attack by an atypical demon leads him to meet B, an assassin and old friend of his brother. Against his brother Christophe's wishes, Yuuki is thrust into the world of assassins, Relentless, and everything non-human he’d only barely scratched the surface of as one by one every being in the universe seems to be after him, but for what reason only Christophe and the leader of all assassins, Grimmrod, seem to know.