Reinventing Magic: An Inventor's Tale - Chapter 100: The Herald’s Warning

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

Satou Shiki a Japan present-day university student suddenly one day he got attacked by a slasher when he open his eyes he was already transferred to another world’s labyrinth city. In that another world he who was awakened to do a lot of “things”.

Han Yang never thought he would one day sell himself into a marriage with another man. He believed his life would be mundane but that man, named HeLian Qing, broke his pre-planned life. Parental debt, a child’s compensation, he had no chance whatsoever to resist, he has no ability to resist.

Until he became the lowest-ranked master, his lonely and luckless life never changed.Suddenly one day, a descendant injected him with a nanomachine, and the machine started ‘speaking’ to him.[I am the seventh generation Nanomachine manufactured by Sky Cooperation, and I am operating as a central nerve connected to your brain.]“What? What are you talking about?”This was beyond the boy’s knowledge, he turned pale.The Nanomachine linked to his cerebrum realized the User was not understanding a single word it said.“Who are you, and why are you doing this to me?”[“I am the seventh generation Nanomachine.]“Nano Machine?”[Yes, Nanomachine.]The boy’s face hardened.Mashin was the deity the Mashin Religion worshipped, along with the Sacred Fire.The religions’ Master communicated with Mashin.“Um, are you really Mashin?”The boy knelt down and asked with a trembling voice. At this, the Nanomachine attached to his cerebrum realized it had been misunderstood.