'Lust system': Rise of the Harem lord - Chapter 31: goddess of Pleasure and pain

Among the demons, the supreme ones are called “Great Saints.”

A young man leaves his mountain village and travels around the world. By unceasing efforts, he finally becomes a legend of the age.

- Description from Novelupdates

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

This is a story of a man named Kim Sae-Jin, who one day, inexplicably wakes up as a Monster. Follow him and his perilous journey to get his life back as a Human, all the while growing even more versatile as a Monster in the process. This should be… complicated, somewhat.