Souhei Saino has always aspired to become an adventurer and travel the world with his parents. However, when his parents never return from their mountain trip, Saino is left all on his own. Even still, he perseveres to make his dream a reality, giving his best in every aspect of life. One day after coming home from school, Saino is astonished to discover that his basement is not exactly as he remembers. Previously a cramped storage room, the basement is now an enormous labyrinth filled to the brim with monsters and treasure chests. The appearance of this new place now enables Saino to realize his fantasy as an adventurer. However, to increase his level in the labyrinth, he must regularly copulate with any women he desires. With the help of a few magic tools, Saino resolves to make it through this dungeon, even if it means exploiting every girl he likes! [Written by MAL Rewrite]