The Kingdoms of Ruin.

Witches were once respected for the wisdom and magic they gifted to humans. But with the rise of the Gear Expansion era, the new science community deemed them as enemies who hindered the progress of society. Thus began the slaughter of all witches, including one who had mentored a human boy named Adonis. After witnessing her death, Adonis vows to bring bloodshed and terror to the human race.