Tartaros: A mysterious and massive underground dungeon. There, adventurers are engaged in a night and day struggle to find the treasure they seek. Lavi the New Adventurer is taking on the challenge of Tartaros, but has a problem. A renowned dark merchant, Philo the Beastkin, is pestering him to buy her strange items! She pushes items (often erotic) onto Lavi for him to use in every situation they come across. What will become of Lavi's adventures!? Is he willing to buy anything from this adorably annoying merchant girl!?