In the year 2045 A.D., Earth is invaded by four different worlds. To defend the planet, one must conquer the dungeons connected to each of these other worlds. Each country selects \explorers\ to take on this task, and Gunma, an ordinary man chosen in Japan, is suddenly thrown into the front lines of the attack! Scared and over-equipped, he activates his \listening ear\ and \enemy searching\ skills. Then, he encounters the strongest and most beautiful girl in all of mankind! While being pushed around by the girl, who is too strong for her own good but has a tofu mentality, he rushes through the dungeon at breakneck speed... This is an unprecedented dungeon fantasy that loosely knocks down everything!