Adventurer Rabi (Shota) aiming to become strong by conquering the largest dungeon in the continent, Tartaros. While exploring the dungeon he was caught in a trap and there he met a Ponkotsu Merchant named Firo. By saving Rabi, he is forced to sign a contract with Firo to be her customer by buying her weird items. Now, Rabi set off his adventure with Firo and her weird items.