The Warden of The Witches - Chapter 114:

In a world where martial artists reign supreme, strength is everything. Unfortunately, that logic doesn't apply to a certain Florida Man.

Refined in the nuclear fallout wasteland, Leo was the strongest mutant alive. He carried an alien artifact, allowing him to exchange his lifespan for modern items. After 50,000 years of solitary life in a humanless world, he collected enough lifespan to transmigrate to another habitable world.

Leo was later thrown into a mysterious planet. He soon discovered that his body produced radiation, and it mutated the surrounding plants and grasses. Worrying that he might ruin the beautiful planet, he chose to live in seclusion.

Unfortunately, the local population soon discovered his existence, and a misunderstanding ensued.

Ou Renjin likes keeping beautiful young men because he likes watching the drama.

Watching them be arrogant and conceited; watching them be obsequious and sycophantic; watching them have ulterior motives and fight with each other, seeing all the evil side of human nature.

Until, he picks up a poor little guy.

The poor little guy is ignorant and helpless, treating Ou Renjin as his whole world, spending all his salary to buy him gifts, standing in front of him in times of danger without hesitation, even…

…saying to him in the calmest and lightest of tones after knowing that their heart matching is successful, “I am very grateful that you have been hiding it from me, but I have long been ready to give my heart to you.”

* * *

036 was born as a test subject, without parents or friends.

As the only successful “petri dish of renewable organs”, he had every organ in his body cut out and transplanted to the rich and powerful countless times.

After getting used to the pain, he met the most special person in the world.

This person was so good that he wanted to cut out his own heart immediately.

- Description from Novelupdates

King Grey has unrivaled strength, wealth, and prestige in a world governed by martial ability. However, solitude lingers closely behind those with great power. Beneath the glamorous exterior of a powerful king lurks the shell of man, devoid of purpose and will. 

Reincarnated into a new world filled with magic and monsters, the king has a second chance to relive his life. Correcting the mistakes of his past will not be his only challenge, however. Underneath the peace and prosperity of the new world is an undercurrent threatening to destroy everything he has worked for, questioning his role and reason for being born again.