Another Stupid Isekai - Chapter 925 T.D.O.N.B: S15C, Part X - The Fallen

The world is big, but I am the only one who is orthodox.Sweeping the world's immortal sects with the power of the Celestial Dynasty.A strong man who practiced the 'Way of the Emperor' came to a world full of immortal sects, and a secular dynasty that was despised by the practitioners gradually came to be on an equal footing with all the top immortal sects.The law of the dynasty is that everything in the world is the king's land, and the shores of the land are the king's ministers! There is only one orthodoxy in the world, and all immortal sects are illegal organizations!

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.

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.

On the vast sea, Aokiji stopped a ship. After a great battle, Aokiji smiled helplessly, “Hey! Brother! Don’t waste your efforts! I am a natural-type ability! You can’t beat me of!”

Before the words were finished, a sword qi flashed across, freezing thousands of miles away, the frozen Qingzhi’s head crashed immediately, I was afraid that I ate a fake frozen fruit.

In the second half of the great route, Huang Yuan hummed incoherently, “Brother! You said you are faster than me! I’m so embarrassed!”

Before the words were finished, a figure stood on the flying sword and fled thousands of miles away in the blink of an eye, leaving behind a bewildered yellow ape fluttering in the wind.

Kaido: I am a blue dragon!

Someone: Sorry, my sword is also called Dragon Slayer!

 …

This is a sword story, but also a legendary story!

Of course, it is also a miracle that happened in One Piece.

- Description from novelbuddy