Hikari: Rise Of The Weapons Master - Chapter 175 Lance

Gu Qingli, a modern-day doctor and poisoner, was killed by her best friend. She was reborn as a weak peasant girl who could easily be bullied. Not long after she returned home, her wedding was called off. Everyone in the village started speaking poorly about her. A greedy matchmaker showed up and tried to convince Qingli to marry an older man! The matchmaker had barely been gone for a few seconds before returning once again. It seemed that Xiao Laosan, a man from the same village who was famous for bringing bad luck to his partner, wanted Qingli as his wife. The matchmaker wondered why a wretched woman like her was so popular. Gu Qingli did not mind. She thought that she, a wretched woman, was a perfect match for this man. For the days to come, she'd take her younger brother with her to forage for herbs, and they'd stir up trouble when they got bored. Wretched woman? A failed investment? Those things had nothing to do with her!

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.

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!

“Any who don the title of 'king' or anything of the sort in my presence is nothing more than an ignorant fool. This is my land and I shall be reclaiming it soon. I am Cacophony, the Vampire Empress!”As those words left her lips, every cell in my body reacted. It was unreal—no, it was otherworldly. Her beauty, her power, and her overwhelming arrogance. It might've been then that I realized that my normal life had ended.How did it come to this?Ah, it was curiosity. Yes, a deathly curiosity brought me to that graveyard that day.It was there that I stumbled upon her coffin. I had absolutely no clue what I was doing then, and even now I have no idea what possessed me to touch it—that single moment changed the course of history for the entire world. I found myself delving into a completely unknown world.Should I regret it? Maybe. But the truth is, I don't.Exploring the world’s hidden secrets, forging unexpected bonds, and living alongside the revived empress—it’s exciting.“Even if it's wrong, I think I'm going to enjoy every moment of it.”