The Simple Life of Killing Demons - Chapter 54Book 10:

Xiao Ze, who was dedicated to the people and vowed to become a generation of Ming Jun, accidentally fell on a little lady.
The little lady was born beautiful and lovable.
So Xiao Ze accepted his life and got the name of fear.

ps:
①The male protagonist has no concubine, and he is dedicated to serving the country.

- Description from novelbuddy

Lin Xiao was an orphan who strived to get stronger while living with his sickly younger brother in an unnamed small village.

Lukas was forced out of high school before he could undergo the Awakening Process. His dreams of starting a new life by becoming an Awakened were shattered.Becoming an Awakened with supernatural powers meant being bestowed with riches and all the resources needed to fight off the invading hordes of demonic beasts.Lukas received the Slaughter System instead. With every kill, he was able to grow stronger and gain new abilities.[Ding!][Congratulations on Host’s first slaughter.][Current Slaughter Points: 1/500][Host Level: 1][Please Select New Ability]Soon, he was able to fighting off demonic beasts invading and move up the ranks.

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