MTL - Don’t Covet the Beautiful System!! - Chapter 95

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

Crossing to One Piece world, he became Roger’s younger brother.

Ye Feng was transported to a cultivation world, but unfortunately had no hope of cultivating immortality and could only live as an ordinary mortal. He only wished to live a peaceful life.Yet he didn’t know—The dog he adopted, because it ate his food, became a legendary demon king.The kitchen knife he casually forged became a peerless divine weapon, causing numerous experts to fight desperately for it.The young disciple he took in became an immortal lord that led an era, due to cultivating the techniques Ye Feng taught him.Even the skeletons he looked down on the most were ominous demon kings that suppressed countless worlds.Many years later, looking at the void shattered with a punch, Ye Feng murmured to himself: It turns out the peerless kings were myself all along…

I got transmigrated into a game I’ve never seen before.

I thought it was a top-notch RPG and spent 30 years on it.

I retired as a war hero and planned to spend my remaining time leisurely.

But it turns out, it was an academy story?