“Dungeon Slayer. I am revoking your explorer’s license.” “….What?” Once, dungeons were feared by people as monster nests. However, in recent years, the resources sleeping within them have become important, and people have come to coexist with dungeons. As a result, Lekt, an explorer who had destroyed countless dungeons through ‘complete conquest’—the ‘Dungeon Slayer’—was cast aside by the nobles who profited from dungeon management and expelled from the Explorer’s Association. Retiring from active duty, Lekt, thinking it couldn’t hurt to rot, took a job as an instructor at a dungeon training school introduced by an acquaintance, hiding their identity. But… “Why is the instructor so strong!?” At first, the students looked down on Lekt, who had retired young, but before long, they began to worship them. “Because you retired, the dungeons are becoming more active!?” “Coexisting with dungeons is impossible!! The upper echelons of the country don’t understand!!” Lekt was even begged by veteran explorers to return to active duty, and it seems they won’t be able to live peacefully. The schemes of the nobles. The changing dungeons. Lekt, now free, casually appears and influences them. This is a pseudo-after story of a hero who thought their role was over and sought peaceful days, but unknowingly continues to have a great influence on the world.