Soul Emperor Martial God - Chapter 10 - 9: Xiao Yi’s Plan

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!

[The Demon King is Dead], a story in which the Demon King got immediately killed in the Prologue. I became the ‘Demon Prince’ of said novel.

…Help me.

After being imprisoned in the basement by her mother for ten years, she ended her cruel and tragic life in death when they forced her to hand over the key to the hidden treasure. Getting reborn in her teenage years, she woke up in the bed of that terrible and powerful man. This time, she must take revenge on her enemy, and now she must live.

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.