The demon lord won. All that are left are demon drones (all male) that hoard over all the resources and rule the world with an iron fist, and various women and children, who live in poverty under the foot of their oppressive rule. Desperate to keep all sentient life from growing extinct, a goddess reincarnates a man as a demon with one task, to get the demons interested in having sex with the female survivors and make babies. With that task, he decides to start this world's first brothel, where demon's obtain pleasure, and women obtain wealth and power by using their bodies. In this world, the oldest profession has become the newest profession, and this reincarnated demon is going to make the most of a skyrocketing enterprise.