Three years after monster-infested dungeons start appearing on Earth due to an American experiment gone awry, anonymous researcher Keigo Yoshimara strikes gold when he accidentally kills a creature. This earns him a magical "D-Card" and a mysterious skill that allows him to see RPG-style stats. Deciding to quit his job and go into dungeon diving, Keigo seeks the assistance of his highly knowledgeable colleague, Azusa Miyoshi, to help him conquer the dungeon exploration market and make millions. But it's a face to obtain all the treasure and magic he can before the masses amount of government agencies and like-minded explorers take it first. No one said getting rich would be easy!