Kuma Kuma Kuma Bear - Chapter 276: Bear-san Prepares for Battle

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.

The Supernatural era descended, the rules changed, mystery arrived, and the world altered. Countless ruins of civilization emerged, and an abundance of Heavenly Materials and Earthly Treasures lay at everyone’s fingertips. Radical faction, “This is the best of times, entering a new world, excavating relics, mass evolution!” Conservative, “This is the worst of times, with countless monsters outside, once you leave the Safe Zone, extinction awaits humanity!” … Meanwhile, at a remote ruin, Lu Yuan successfully discovered new treasures and sought after the mysterious wealth, desperately trying to contact his fellow Earthlings. “Found a communicator, can it get through?” “Hey, humans—I’m almost becoming a god, and you’re still hiding in the Safe Zone?”

Shi Jin was a desperate woman and just a pretty face in her past life. She was swapped at birth and brought up in a rich family, only to eventually die a horrible death.