My wife and I got Reincarnated in Martial World - Chapter 2: New Beginnings

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

When I cleared the final chapter of a game that was a national failure, I became an unnamed side character in it.

A non-standard, unmeasurable, EX rank supporting character.

In a world where beast masters rule by taming magical creatures and competing in thrilling tournaments, becoming the most celebrated sport, Eratz seemed destined for greatness. Surrounded by friends and family, his path was set until a shocking betrayal shattered his dreams.Fueled by the pain of his betrayal, Eratz looks up at the night sky, finding a new purpose. He vows to rise from the ashes and conquer the beast master world, determined to become the greatest and reclaim his lost honor.

Li Pu, who has the blood of a summoned beast, originally just wanted to lie down honestly, but found that his talent as a summoner seemed a bit unusual…

- Description from novelbuddy