Hametsu no Oukoku

the kingdoms of ruin - Witches once blessed the human race with wisdom and peace. But the Redia Empire's "Gear Expansion" brought about a culture of science that far surpassed magic, and witches were viewed as enemies impeding the progress of civilization. Thus began the witch hunts. One human named Adonis, who was raised by a witch named Chloe, swears revenge against the human race that took his beloved mentor from him. What salvation can be found at the end of a bloodbath fueled by utter despair?

(Source: Crunchyroll)