One Piece: Supreme Check-In System - Chapter 48: Voidreign Kingdom Appearance

Many islands dotted the vast oceans of this world. However, some of the islands were a lot more sinister than the rest. Those islands, known as Nightmare Islands, were true nightmares to all but the strongest and most fortunate. Children were kidnapped and thrown on these isolated islands by the Nightmare Palace, forced to sign soul pacts with evil soul pets: Nightmares. These devils slowly devoured the souls of their trainers to grow stronger. If the children did not cultivate fast enough, their souls will be devoured whole, leaving only an empty husk behind.

Chu Mu, the protagonist, was an heir to the Chu Clan, but due to a plotted murder, he was thrown on the island, sentencing him to almost certain death. Dancing on the edge of life and death, he struggled to survive with a small Moonlight Fox he captured. When he finally escaped the devilish foremen on his island, he couldn’t help but let a breath out. But little does he know, the experience was only a beginning to a fated journey with his little Moonlight Fox…

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

SLASH!(So this is death?!!)I, Elysia, found myself dead before even reaching the Demon King's lair, and our Hero Party was completely annihilated.And this was done by none other than a fellow human—my former classmate.He had been mostly invisible during our time at the academy, but then he started committing one crime after another until he became a lackey of the Demon King.Who would have thought that the strongest party of humanity would be wiped out by humanity’s traitors?(If I could go back to the past, I swear I will kill you!)Just when I thought I could finally pass on, I opened my eyes.Five years back, when I first enrolled at Arcadia Academy.And there he was, the traitorous bastard of humanity...****“Huh? Where am I?”One day, I opened my eyes to find myself in an unfamiliar place and came to realize this was the world within the novel Savior's Dawn that I had read.Everything seemed to be proceeding the same as in the novel—except for one thing.The main heroine is glaring at me as though she wants to kill me.Could I survive with the main heroine after my life?