Just before being summoned to another world, the protagonist’s summoning medium was secretly swapped by someone. As a result, he was not summoned as the "Holy King" but instead as the "Sex King."

The magic he can use includes water magic in the form of lotion, fire magic as candle wax, and his summoned beasts include a wooden horse used for punishment…

Branded as "vulgar," "useless," and "filthy," he is rejected, has his engagement annulled, and is ultimately exiled. However, the one who picks him up is a princess from a nation where the sex industry is legal.

Using his modern knowledge, the protagonist begins rebuilding the nearly bankrupt sex kingdom. He introduces new fashion trends unknown to this medieval world and uses his authority as the Sex King to subjugate the girls. He then establishes modern sex service techniques.

The protagonist's method of leveling up is through intimacy with his heroines (his concubine maids). The more intimate he gets, the stronger he becomes, and the wealthier the kingdom grows.

However, the surrounding great powers will not stand idly by and allow a flourishing nation full of women. Thus, the flames of war are ignited.

Utilizing his creativity, adaptability, and cunning, the protagonist repurposes his sex-related magic for military applications and overwhelms his enemies.

As he gradually awakens to the path of conquest, he begins walking the road of a ruthless emperor. However, by his side is always a heroine, a celestial beauty who keeps his heart from straying too far…