One Piece: Unreal Adventure - Chapter 38: A Small Test

Yeon-woo had a twin brother who disappeared five years ago. One day, a pocket watch left by his brother returned to his possession. Inside, he found a hidden diary in which was recorded “By the time you hear this, I guess I will be already dead….”

The little handsome son-in-law passed through a world as waste material and the husband of a wealthy family. But because of his lacking aptitude, the wealthy family had driven him out. So he worked hard and found a more powerful family’s thighs to hold onto. Soon enough, he became the strongest son-in-law and husband in history.

In this world, it was impossible to practice martial arts. It was futile so he might as well take advantage of his wife’s thighs and maintain a comfortable and leisure lifestyle.

He’ll train his wife to become the strongest and best person in the world.

“Whoever dares to provoke me, let my wife kill you!”

- Description from Novelupdates

“How many people have you killed? How many families have you destroyed? How many towns and cities have fallen because of you!?”“I don't remember.”The villain whom the main character was destined to defeat at the end of the novel. That was who I had become.There was just one problem...“Why am I a teenager!?”“Why is there a school acceptance letter on my desk!?”

The figure of the Armada seems to be still riding the wind and waves in the Atlantic Ocean, and the gold of South America still seems to flow in continuously. As Alfonso from the Bourbon family returns to the Royal Palace of Madrid where he was born, the story begins here…

- Description from novelbuddy