Clay has become accustomed to his work in the dungeon. He learns more about the secrets of slimes and bats, experiences potion refining for treasure chests, and observes the production of skeletons and zombies, uncovering further hidden aspects of the dungeon. Meanwhile, his exploration skills are gradually improving as he learns to handle magical power, and he is advancing through the exploration of the 9th underground floor...!? This is the 4th volume of the dungeon management fantasy!