Master Bai! This Celestial Fox Spirit Is Asking For Divorce - Chapter 25: Episode 4.2 Targeted

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.

Yun Bixue is in dire straits—

After a tear in reality pulls Kagari Shuya into a white room he discovers a futuristic interface for reincarnating in a different world. After looking through the different races and skills he unlocks a new race, Lucivault, a type of vampire with none of its characteristic weaknesses. All set to start his life in a new world, Shuya is confused to discover that he is enveloped in darkness. As it turns out something went wrong when he was transported and instead of appearing where he was supposed to, he appeared in an underground cave. Shuya faces untold dangers, runs for his life, before finding his way out of the underground world. After escaping he meets his Shishou and begins to learn to fight with a spear. There is also a cute black cat named Rollo.