In the realm of Reinbulk, a fabled Hero once vanquished the Demon King in the Kingdom of Leezalion. Now, five students are called back to face the Demon King's resurgence, summoned by Luxeria. Among them is Yashiro Yuu, lacking magical powers and unrecognized by Luxeria. Little do they know, Yuu is the previous Hero who sealed the Demon King. Perplexed by the unnecessary summoning, Yuu opts to step away from the heroic duties, content that the world is safe for now. Choosing the path of an adventurer, he leaves the fate of battling demons to the new generation.