The Hero is An Academy Librarian

Ten years ago, the Kingdom of Aquinas was thrown into a bloody war that saw the humans pushed to the brink of extinction by the much more powerful demihuman races. With superior genetics and magic, the demihumans captured the majority of the human territory, and it seemed like all was lost. But all that changed when the mysterious mage, Verati, appeared on the battlefield. With unexplainable power and unparalleled skill, Verati boosted the human army and pushed the demihumans back from their land! The demihumans did everything in their power to try and regain the upper hand, but Verati was a power beyond their comprehension, and after they realised that they could not win, they were forced to surrender to the humans. Rut rather than killing the demihumans, Vertai decided to show mercy, and he convinced the humans to forge peace with the demihumans. Verati stood as a witness as a peace treaty was signed between the two races, and both the humans and demihumans created the Verati Magic Academy in honor of the man who returned peace to their land. ...... Percival was a simple library keeper in the Verati Magic Academy, and he spent his days doing magic research while enjoying his time with his family. But those peaceful days were threatened when a dead body emerged in the middle of Percival's library. Now in a world of mystery and intrigue, Percival must figure out the truth behind the murder so he can gain back his peaceful days. .... This is a rewrite of the book. I hope you enjoy it. — Description from novelcodex.org