In a world that revolves around a single trade, Dungeon Crawling, one boy has dreams of making it big as one of the Crawlers, those who make a living clearing the seemingly infinite floors of said dungeon and bringing cores of monsters out to be used to power society. However, there's one simple problem, he's not even strong enough to qualify for the lowest rank of the Crawlers. Happenstances causes him to inherit a new power, and with his dream fufilled, he becomes the Savior.