A century ago, King Kyle of Orvelia defeated the demon lord Angmund and brought an era of peace to the world. But now, demons have reappeared in the forests, threatening humanity once more. A scouting party is sent to investigate, yet only a single soldier returns alive. Meanwhile, Riheet, the leader of a dark elf mercenary group, schemes to seize Orvelia as vengeance against the humans who abandoned his race a hundred years earlier.
Knight apprentice Kasel, accompanied by the priestess Frey, sets off to rescue Clause, an old friend who vanished during the ill-fated mission. Along the way, Kasel learns that he is the son of the legendary King Kyle and the only one capable of wielding the holy sword Aea—the very blade that slew the demon king. To fulfill his destiny, the young knight must embark on a dangerous journey, unseal the sword, and put an end to the terror the demons have unleashed. As Kasel's quest to restore hope to humanity and Riheet's path of revenge converge, what fate awaits them?