After Rista and Seiya retreat once again to the Divine Realm, Aria proposes that Seiya train under the tutelage of one of the Gods there. A looming crisis on Gaeabrande compels the pair to return, and seek out companions to aid them in their quest.

A delegation of Roseguard Imperial Knights summons Seiya and the others to a nearby fortress, where a wing of demon houseflies is attacking from the air. Seiya offers his help, but when he butts heads with the knights' leader, things turn ugly.

In violation of Divine Realm law, Rista opens a portal directly to the location of the final boss fight, where Seiya and the Demon Lord are locked in mortal combat. Seiya resolves himself to make the ultimate sacrifice to defeat the Demon Lord.