Three years earlier, a mission at Area 51 turned sour, and Earth was suddenly populated with dungeons. From regular people to soldiers, thrill-seekers traversed these catacombs in search of riches, power, and enchantments. Keigo Yoshimura, a boring salaryman who dreamed of retiring, found himself in the middle of the action while working. He stumbled upon a new dungeon and acquired a magical skill, converting cave exploration into RPG-like gameplay. Before Keigo knew it, he was the top explorer globally with Azusa Miyoshi, his smart and business-savvy colleague with whom he partnered. Together they worked to turn Keigo's knowledge into profits, examining the status panels for clues. Keigo, on the other hand, drew the attention of the military, governmental organizations, and more nefarious entities, endangering his fantasy of living an easy life.