I'm the Mysterious Leader of the Salvation Organization - Chapter 483:

High school student Mikoshiba Ryouma was summoned to a different world in the middle of a war. Sensing the malice from the one who summoned him (a summoner of the O’ltormea empire), he uses his martial arts to run away, killing important people of the empire during his escape. After the escape, he rescues two twin sisters from the hands of thieves. The sisters who can use magic, swear to serve him as subordinates. Thus, Ryouma begins his journey on the path of the supreme ruler.

Yu Zhengdu joined a small start-up company that claim to offer “life management services”……as a programmer.

On his first day in office, he received a phone call from a stranger: “Hello, I received a text message from your company that informed me of my reincarnation tomorrow……”

Yu Zhengdu: “……??”

Shang Que, the beautiful little boss, said, “New employee, welcome to the Hell organisation in the human world. A thousand years ago, I was known to the human world as the Ghost King of Luofeng Mountain.”

Yu Zhengdu: “……??” From then on, he was incredibly distressed about the development of Hell.

- Description from Novelupdates

Son of a bitch! I just finished this godawful fantasy novel, and now I'm knee-deep in it – as David, the disgraced son of the Solarian Empire's top general! Talk about some twisted cosmic joke. But hold on a damn minute... maybe this isn't all bad. Armed with the knowledge of that trashy plot, I can become the ultimate shadow player, an overlord perhaps. Screw the damsel-in-distress harem too – it's time to pull the strings and become the real power behind the throne. This isekai might be a steaming pile, but I'm rewriting the ending with a little more... Debauchery (wink wink).

The end of the world is full of crises, but Su Chen says not to worry because he has the Red Alert System. That’s how confident he is. You say you have a lot of weapons? Sorry, I have more weapons than I can use here. Let me introduce you to the weather control device. You say the mutant beasts are very powerful? No problem, I have a way to deal with them…