The continent of Atlatan is once again consumed by the fires of war following a horrific incident known as the Great Hall Tragedy. What was intended to be a joyous event establishing peace between the Fantasia Union and the Factory Alliance—the marriage of Sir Alexis Douse and Lady Marrine Kreische—turned into a disaster. As the bride and groom walked down the aisle, the ceremony was abruptly interrupted by a powerful convergence of "Chaos," a dark energy from another dimension that corrupts the land and summons monsters and demons into the world. From within that energy emerged the Demon Lord of Diabolos, an evil entity who instantly killed the archdukes of both factions, shattering any hope for peace between them. Having failed to prevent this catastrophe, Siluca Meletes, a mage of the Alliance, travels through the Chaos-infested countryside to study under a master magician. When she is intercepted by a group of soldiers working with the Federation, Siluca is rescued by Theo Cornaro, a young warrior carrying a mysterious "Crest," a magical symbol that gives its wielder the ability to banish Chaos. Bearing no allegiance to a specific domain, Theo hopes to attain the rank of Lord so that he can liberate his hometown of Sistina from its tyrannical ruler and the Chaos spreading within it. Impressed by his noble goal, Siluca enters into a magical contract with Theo, and the two embark on a journey to restore balance to their war-torn land.