The Ruler Of Darkness - Chapter 8Book 4:

What got summoned was the world’s strongest sociopath.

The strongest man of the cultivation world, Yu Hua had sent the Grand Supreme Elderly Lord, Chi Hou to cultivate. After cultivating, Chi Hou was unrivaled for hundreds of thousands of years. However, he was ridiculed by the Demon Lord to be a bachelor who is as old as bone ashes and a fossil grade single dog. Not to even mention a girl, he doesn’t even have a little sister. In order to reverse the game, Chi Hou decided to kidnap the Demon Lord’s precious sister and turn her into his own little sister. He’ll first save her, then raise her, teach her magic, feed her dinner, tell her bedtime stories, and give her rare treasures. Like this, he’ll be the perfect brother. She won’t even remember her real brother.

Little sister: “What does this pervert who pulls me up every night to tell me ghost stories want to do? Cultivating to become a celestial is too hard, I want to go back to Earth!”

- Description from Novelupdates

Once through the pirates, Lu En became the son of Monkey d Dragon, a grandfather named Monkey d Karp, and an unreliable and neurotic younger brother named Luffy.

Fortunately, the ghost back system is activated!

The completion of the ghost back is 10%, and the training effect is increased by 100 times!

The completion of the ghost back is 20%, and the training effect is increased by 1000 times!

…

One day, Lu En, a ghost-backed master, appeared in front of Luffy who was shouting to go to sea, and made Luffy cry on the spot.

Luffy: “The pirates in the sea are all monsters like my brother? I don’t want to go out to sea!”

Garp: “For a long time, the two boys, Long and Luffy, with small arms and calves, I really doubt that they are not my sons and grandsons. Like Lu En, they are the grandsons of the old man!”

Warring States: “The strongest creature in the sea, land and air is Kaido? No, it’s Lu En!”

- Description from novelbuddy

A decade ago, the first dungeon gates appeared, but some vanished before they were ever conquered. The MC, a low-rank hunter, awakens the Lost Gate System, granting him access to these forgotten dungeons where legendary monsters and artifacts are trapped. Each completed lost gate grants him absurd power, but also reveals terrifying truths—these dungeons are prisons for ancient beings who want revenge.