The Wrong Way to Use Healing Magic - Chapter 4Vol 13.

[You have become the master of the Warden Mansion.][Your first quest is to refine mana from one of your maids by having intercourse with her.]When nineteen-year-old Jett Talon suddenly wakes on an emperor-sized bed, he finds himself lord of a mysterious mansion where countless gorgeous maids stand ready to serve. His first companion is Mia, a blonde elven maid who checks his every box. After making love to her, Jett gains mana, unlocks legendary powers, learns his duties as Master of the Warden Mansion, and uncovers its hidden secrets.

There is always such a person in the world, his family background is better than yours, his status is higher than yours, while you work hard and think all the way up, but with just a wave of his hand, you are wiped out. What is even more sad is that he doesn’t even know who you are.

Zheng Jue met Han Jin like this but he didn’t realize this truth until he died. In the end, he had found the wrong opponent and ultimately lost his life.

- Description from Novelupdates

In order to live he must get close to girls, what kind of rule is this? Tang Zheng possess the Nine Yang Saint Body, a rare body constitution that is hard to come across within a millennium, yet he must absorb pure Yin energy to stay alive. In order to live, he will fight! Absolute campus belles, goddess teachers, charming housewives, haughty lolis… all kinds of woman walk into his life causing him to be surrounded by beauties!

Chen Rui, an otaku from earth, is reborn into a human body in another world, who falls into the legendary evil, brutal world of the devil called Mozu where humans are treated as food. He has to survive while facing horrors of the devil, violent dragons and a variety of powerful enemies by depending on a strange super system chip and his wits. Surrounded by Devil’s beauties such as black-bellied lolita princess, cold queens, violent dragons, charming poisonous devils …

Wanting to live in the Devil’s world is hard! Wanting to live in the Devil’s world as a human is harder! Wanting a human to be the devil’s son-in-law is hardest!

Let us see how a small otaku uses power and strategy step by step starting from an ordinary human to writing a legend as the devil’s greatest son-in-law.