In 2018, dungeons, once thought to be figments of imagination, suddenly appeared worldwide. Five years later, in 2023, 41-year-old Naoto Yamagishi, a call center worker, finds himself unemployed. While opening a drawer in his work desk, he discovers a miniature dungeon inside! He can level up by defeating miniature monsters, but the dungeon has a drawback—no drops. Undeterred, he decides to max his level before tackling other dungeons. This is a fictional story and is not related to any real people, organizations, or events. This novel won 1st place in various categories on Shousetsuka ni Narou (Let's Become Novelists).