Isekai Maou to Shoukan Shoujo no Dorei Majutsu - Volume 10 Chapter 5 part6

The Blood Warrior of the Ungpae Association, who created a sea of blood wherever he went, made the world of the Forces of Evil possible.

The Nine Great Sects and the Six Great Clans joined forces to fight him, but were unable to stop him.

Four Great Warriors, who were Murim’s last hope, appeared.

The four of them fought against the Blood Warrior and eventually defeated him at Mount Song.

The time has come for the legacy of the Blood Warrior to rise once again.

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

“I will have my vengeance, in this life, or the next!”Albedo died alone and depressed and was reborn in a Novel he had been reading. However, instead of becoming the Protagonist or Antagonist, he becomes Albedo Neverwinter, an Extra he couldn't even recall from the Novel.However, the cruelty of life didn't change even after rebirth, and his new family was ripped away from him, leaving him with nothing but scars as reminders of the gruesome fate his family faced.Promising to get his revenge, watch as Albedo, alongside his System, his tactical mind and scarce but valuable future knowledge, rises up the ranks and ascends the pyramid of power.[ OP MC, System, Harem, Romance ][ Yeah there will be Smut, but it won't dominate the Novel ]

The scum’s or villain’s long road of transformation was tentatively set to the world:
The abandonment of the educated youth’s wife (Completed)
The hidden marriage of the scum film emperor (Completed)
The best brother in the world (Completed)
The Phoenix male who destroy the bridge after crossing the river (Completed)
The treasonous general (Completed)
I’m an honest man (Completed)
To become the top scorer in the School of Agriculture (Completed)
The soft rice man’s self-cultivation (Completed)
The whole world is reborn (Completed)
I want to survive on a desert island (Completed)
The stallion male who has seized the opportunity (Completed)
The perverted self-salvation (Completed)
The spring of the loafer (Completed)
The misplaced life (Completed)
The miser career (Completed)
The ghost is out of feeling (Completed)
The Queen’s favorite husband (Completed)
The vicious girl with her godfather (Completed)
I want to be a good person (Completed)
I does not tear up the family (Completed)
The perverted common plant (Completed)
The Mary Sue’s men (Completed)
Every time I was reborn, someone wants to kill me (Completed)
The old people’s counterattack path (Completed)
The global evolution (Completed)
When I became a net red (Completed)
For you, good person (Completed)
His heart had white moonlight (Completed)

- Description from Novelupdates