MTL - Girlfriend Needs To Be Coaxed Every Day - Chapter 6

A data loving young man from Earth has an accident which transports him to a dark land filled with terrifying creatures and magical powers. Fortunately for him, he has a Biological Assistance Chip to ease his path. However, things in this bizarre and strange world are not always as they seem, and, though it is a tremendous asset, the chip doesn’t always work as expected. With all of the crazy creatures and magical mayhem around him, one can only wonder what the future holds for this young man…

- Description from novelupdates

Just as a gamer found an overpowered skill book called ‘Item Upgrade’ in the hottest virtual reality role-playing game on Earth, something happened to the game’s system, causing his soul to leave his body and go to another dimension. Common sense dictates that he would be born anew then become the greatest overlord of this world by making use of his advanced knowledge. Not in this case! He was already dead. Only some fragments of his soul and that skill book managed to get into that dimension and merge with an ordinary common youngster called Bai Yunfei.

This was the enormous Tianhun continent, where humans could be said to have no limits. There was a group of humans here who could cultivate the power of their own souls then control their bodies, the natural elements and even other people’s souls with that power! These special beings were called — soul cultivators. Come witness how the several fragments of the dead inter-dimensional traveler’s soul and that skill book, which was not governed by the laws of this plane, were going to help Bai Yunfei become a legendary soul cultivator and craftsman!

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates

A Hentai World is a Dangerous Place, Especially if Your Best Friend is a Hentai Protagonist and You Are a Trap.