Use Me Like A Drug (omegaverse bl) - Chapter 134: Welcome home, pup.

Traveling through the world of pirates, becoming Luffy, and possessing cheats in teaching space, it is natural to make changes.

When Chambord landed on the island, the pacifist, the general Huang Yuan, appeared, and all the supernovas fell into despair except the hat group.

Seeing Zoro sweeping the world with a single sword, Sanji the Demon Kazekaku, and Luffy blasting away the oracle with his four-speed karma fist gun, the supernovas were stunned.

“Is this a supernova? I’m afraid it’s not the imperial group!”

During the war on the top, the hat regiment descended with the momentum like a royal regiment.

On Ghost Island, Kaido and Big Mom satirized: “Hey, boy, what are you going to become? Say it again in front of us!”

Luffy opened five gears furiously, his fist was as huge as a ghost island! A five-speed Yehuo fist gun! Party Kaido and Big Mom!

Luffy landed, the black stand-up collar cloak fluttered, put on the helmet, and whispered domineeringly:

“I’m Monkey d Luffy, the man who wants to surpass you and become the One Piece!”

- Description from novelbuddy

The celestial celestial beings who lived for more than 100,000 years were born and reborn in a small monk in a human world.
His motto: “It’s not as good as a medicinal medicine for ten years of hard work.” “Even if you practice a copper-iron bone, it’s not enough for my soldier’s attack.”

- Description from Novelupdates

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

When Simon dies, it turns out there's more to combat than lightning reflexes with his controller, and the path to becoming a hero is more brutal than he can imagine as he descends into The Pit. Death after Death is a dark, time loop/Isesaki story with roguelike elements, that explores some of the common tropes in a different light.