The continent of Atlatan has fallen into turmoil after the Great Hall Tragedy, a catastrophic incident that destroyed the fragile peace between the Fantasia Union and the Factory Alliance. The wedding of Sir Alexis Douse and Lady Marrine Kreische, meant to unite the two factions, was overtaken by a surge of "Chaos," a dark dimensional energy that summons monsters and demons. From this corruption emerged the Demon Lord of Diabolos, who killed the archdukes of both sides, crushing all hope for reconciliation.
Siluca Meletes, a mage from the Alliance, journeys through the ravaged countryside to study under a master magician. On her way, she is rescued from Federation soldiers by Theo Cornaro, a young warrior wielding a mysterious "Crest" that can repel Chaos. Sworn to no particular domain, Theo aspires to become a Lord and liberate his hometown, Sistina, from its tyrant and the spreading corruption. Inspired by his noble ambition, Siluca enters a magical pact with Theo, and together they set out to restore balance to their fractured world.