The Empress's Gigolo - Chapter 1: Behead Him

An ordinary student accidentally traveled into an other universe and became the king of a small kingdom. He had gotten a “Cheating Code” of life and was able to complete something extraordinary. This is the story about a king that was able to conquer continents and leave behind him an ultimate legend that will be recited between every generation to come.

- Description from novelupdates

Perdi, known widely throughout the continent, is a very famous author of adult novels. But Perdi’s true identity is actually Vivian, the Imperial Night Librarian.

Vivian sends over the fourth draft of her latest novel to her publisher to be reviewed, but her work is criticized because the way she writes hetero s*x scenes isn’t erot*c at all.

“What? So you’re saying I’ll only know what sexual relationships are like after I experience it myself? But what can I do when I’m bound to a chastity contract?”

Unfortunately for Vivian, she had to sign a chastity contract in order to be hired as an imperial servant, and has been forced to remain a virgin ever since. Worse still, only a member of the imperial family could break the contract … but Vivian only has eyes for Ray, a mysterious man who visits the library every night.

But as it turns out, Ray is the imperial archduke and the emperor’s brother! One day, he approaches her with a sweet offer that she can’t resist …

Nine harmonic zither chords shook the universe, who dared to not acknowledge the lord?

Crossing to One Piece world, he became Roger’s younger brother.