The natural disaster came to the Stone Age with magic, and a monster army from outside the territory occupied most of the mainland's territory.

The civilians were killed and injured countless times, and the wizards were helpless until the adventurer discovered that the only weakness of the monster is that the mind will be controlled by instinct.

The only way to conquer them is to control them by training their desires, but training monsters requires strong sexual ability,

So the mainland began to choose the son of heaven, who is extremely powerful in sex, to save the world.