In the year 20XX, fifty years after the appearance of mysterious entities called "dungeons" plunged humanity into chaos, dungeons have become an accepted part of life. Dangerous creatures called monsters inhabit these dungeons, and those chosen by the dungeons receive special abilities like levels, jobs, skills, and magic. Those who enter the dungeons to fight monsters and retrieve resources are called "Explorers." One ordinary-looking boy, newly debuted as an Explorer, experiences an unusual anomaly. Will this anomaly bring change or stagnation? Fifty years after the appearance of the dungeons, the world may be on the verge of transformation.