About thirty years have passed since 'Dungeons' suddenly appeared in the modern world, along with 'Seekers'—people adapted to these dungeons. Munso Daichi, a single, college-educated freeter, wakes up one morning to find himself a 'Seeker.' Seekers possess unique abilities, including levels, stats, and skills. Daichi heads to a nearby dungeon on his bicycle and begins exploring, gradually leveling up, acquiring skills, and earning money by selling magic stones obtained from defeated monsters. This is the story of a young man slowly gaining strength. Note: The story eventually becomes more like a fantasy of a different world. The book series is published by KADOKAWA (Famitsu Bunko label) with illustrations by tef. The manga adaptation is currently serialized in Kadokawa Comics.