Hinata Watari is an overworked office drone buried in endless unpaid overtime. Convinced that “moving his body will spark better ideas,” he takes an unusual detour on his way home—into a dungeon that suddenly appeared in the city. There, he vents his pent-up frustration by using monsters as punching bags while casually exploring the labyrinth. But just as he’s basking in the thrill of mowing down weaklings, he stumbles upon a beautiful girl under attack from a fearsome monster! That fateful encounter turns Hinata’s dull, exhausting life upside down. Thus begins a refreshing tale of modern-day dungeon adventures and exhilarating battles!