Murdering Heaven Edge - Chapter 171:

Every little girl's fantasy is to live a wonderful life full of riches and luxuries. This was the future she imagined, and she was willing to go to any length to obtain it.She was spoiled, pampered, and doted on by her family, and she was proud of herself. She knew she deserved the best, and she went for it. This, however, is where the nightmare began.Wanting to leave the clutches of poverty wasn't as simple as she believed, given the things she had to give up, the humiliation she had to endure, and the numerous things she had to lose. It was not worthwhile.When she thought she had it all, she was slapped in the face with the cold, hard truth: she was only a SUBSTITUTE.And when two of her closest companions turned on her and betrayed her, she was shoved aside and got humiliated by people she used to know.With nothing and no one to lean on, she was forced to make decisions. Decisions that gradually resulted in something breathtakingly amazing.[DING! SIGN IN! THE HOST HAS BEEN REWARDED WITH ******]

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.

She roused from a pool of blood, vowing to exact retribution on those who had harmed her.

Pain, Pain, Go Away is a novel by Sugaru Miaki, also known as Fafoo, author of Starting Over and Three Days of Happiness. Unlike Miaki’s previous two books, Pain, Pain, Go Away is not a rewrite of any story posted to 2ch, but an entirely original one.

The plot involves a young man who becomes a killer (by accident) – but his victim has the power of “postponement,” temporarily delaying her death.