I have Immortality In The Cultivation World - Chapter 1 - : Longevity Dao Fruit

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

Chen Sansi traveled back to the chaotic end of a dynasty, thankfully with the hardworking system by his side. He originally wanted to hunt to earn money and someday go to the Martial Arts Hall to learn some basic fist and foot techniques, aspiring just to be an ordinary rich man. Yet, fate had other plans. With officials imposing heavy taxes and the Martial Arts Hall bullying the citizens, he had no choice but to enlist in the army to survive, becoming an archer. From “archery (entry-level),” he worked tirelessly up to “operating a ten thousand weight bow, where arrows cannot be dodged,” taking the heads of enemy generals from a hundred miles away! From “basic soldier’s spear technique,” he worked tirelessly up to “National Guardian Dragon Spear, growing more valiant with each battle,” standing firm with a spear on horseback, alone turning back the Enemy Army of a million! Years later, Chen Sansi, having campaigned in the south and battled in the north, was truly invincible under the heavens, commanding two hundred thousand of the Iron Cavalry. Watching his subordinates forcibly ascend him to the throne and become emperor, he felt quite helpless: ’You... you have really caused me trouble!’

Knowing she married a wrong guy, what would she do to deal with the subsequent marriage lives?

In order to pay for her brother’s medical expenses, she had to replace her own sister to marry the rich family's elder son . She always thought she was married to the elder one, but she did not know her husband was nominally the younger son He Yi Ning.

He Yi Ning, the real heir of the rich family, the ruthless business emperor, the ruthless workplace tyrant, and her sister’s dreaming husband. When she found out that the person who married her was He Yi Ning, she stunned and asked, “Shouldn’t i be your sister-in-law?” He smiled charmingly: “Are you unhappy with your husband?”