Ghost in the City: Cyberpunk Gamer SI - Chapter 104

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.

“According to prophecy and scientific calculations, the entire world will see temperatures drop to minus forty degrees within three years, and even the earth's core will be frozen within three hundred years.”“What should we do?”“Gather all our strength, build a shelter together with unwavering unity. In the face of disaster, we must stand united, and everyone needs to do whatever they can to ensure a future for humanity!”“But what if someone refuses to work and just wants to eat and be lazy?”“Then let them die! Activate the alchemy golems and large robots, we do not support idlers!”Set in a scenario similar to Frostpunk, with fantasy elements and a steampunk background, viewer discretion is advised.

“I swear I will make them pay with everything I have. I will use my very own blood to sign the documents that will end them if I must!”To Champagne Gold, life was always like a fast-moving truck with no brakes and a drunk driver, one she couldn't avoid.At the age of five, she lost her parents in a helicopter crash. Life after that was one problem to another but she held on... until her grandfather passed away as well.With his death came the loss of her position of CEO and her hard-earned shares. As if that was not enough, she was served with divorce papers and the revelation of her husband's adultery with her cousin.Dealt with one too many blows, Champagne sought to end it all. Perhaps she could be reincarnated or whisked away to another world like the books she read before, but that was not to be. Instead, a mysterious man entered her life.“Rather than escape like a coward, I can give you the power and resources to carry out your revenge. I have but one condition―marry me.”Champagne held her lips between her teeth and took the offer.However, just when she believed her new life was going smoothly, she found out another painful secret. One more painful than any she had discovered before.She had undergone a uterus removal procedure and she didn't even know it.Now Champagne is more determined than ever to get revenge on everyone who wronged her. She would do and give everything to make them pay for taking away something so precious from her.

Kawaki, who was born in the dragon vein of a planet (Altana), first met Umibozu who was traveling in the universe, and his girlfriend, Kouka.Later, he came to Earth by accident and met the teacher who affected his life —Yoshida Shouyou.He also met a group of friends. The most conspicuous among the group of friends is a fool with silver hair and naturally curly hair, a short man with purple hair, and a little devil whose catchphrase is “Not Zura, it's Katsura!”Gintama Doujin, not transmigration.