I Became An Immortal On Mortal Realm - Chapter 34 - 32: The Five Poisons of the North, Lu Yuanjun_l

Kyle woke up in a land of fantasy and magitech. The usual 'I died and woke up' bullshit, skip all that.

Except he used to be a crime lord, and society here is missing that extra kick.

The world is made up of the five elements, and it could be divided into Yin and Yang.

Beneath the heavens, on the ancient divine center continent, billions of lives thrive in the prosperous era of the cultivation.

Across its vast lands, happiness, sadness, reunion, and separation played out in the long lives of those seeking immortalhood.

Light is always accompanied by darkness, and under the radiance of the heavens, there are silent shadows moving about…

- Description from Novelupdates

A polite and lethargic boy was reincarnated in another world as a vampire bishoujo.

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.