A world under control of the evil Empress. You vow to return freedom to the people by conquering the conquerors… but you are a mere and powerless human.
With the help of Lilith, your succubus friend, and other recruited monster girls you are able to defeat the Empress… once. But it’s a victory thanks to the enemy, and when the monster girls revolt you’re set back to square one.
The world remains under their control.
In your quest have learned about a human colony where monster girls “do various things” (wink) to the residents.