Doomsday: I Obtained A Fallen Angel Pet At The Start Of The Game - Chapter 115 - Class Awakening, Eternal Night Demon Emperor!

Our straight (?) bottom woke up ten years into the future and found himself on the bed of his childhood friend… At the start, the bottom was shocked to his very bones, but he soon quickly accepted this premise and found the whole situation to be rather amusing. Precisely then, the bottom once again went back to his timeline — back to when he and the top were just platonic childhood friends.

In regards to the MMORPG Cross Reverie, Sakamoto Takuma boasted an overwhelming strength that was enough for him to be called the Demon King by the other players. One day, he gets summoned to another world with his appearance in the game. There, there are two people that insist “I am the real summon master.” Takuma gets slave-turning magic used for summoned beasts cast on him by the girls –

This is an Isekai styled story, written from the point of view of the protagonist.

Discover the secret of the new, unknown world with Peter, as he sets his first steps in an empty, ruined city. Meet new people from all around the globe. Fight, laugh, and cry.

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