デーモンシティ

On the continent of Barnhedge, there lies a kingdom named Vagrand. The inhabitants of the country are followers of what they call "Vagrand's True Faith", which teaches them, quite simply, to enjoy life in all possible ways, without controlling their desires and lust. As a result, the capital of Vagrand became the center of corporeal pleasures, and its neighbors started calling it the "Demon City". The player controls a Vagrand sex warrior who is sent by the king on a confident mission. But intrigues and uncontrolled lust surround the hero everywhere: opposition in the palace, a young girl named Milk who wants him all for herself, and the mysterious cult of the Blue Moon are all there to make the hero's life hard...

[Edited from Moby Games]