Record of Grancrest War

The series takes place on a continent ruled by chaos. The chaos breeds disaster, but the Lords of the continent have the power of "Crest" (Holy Seal) that can calm the chaos and protect the people. However, before anyone realizes it, the rulers cast aside their creed of purifying the chaos, and instead start to fight each other for each others' Crests and to gain dominion over one another. Siluca, an isolated mage who scorns the Lords for abandoning their creed, and a wandering knight named Theo, who is on a journey to train to one day liberate his hometown, which is under tyrannical rule, make an everlasting oath to each other as master and servant and work together to reform this continent dominated by wars and chaos.