Primordial Soul's Rebirth - CHAPTER 399 - Girls in Ferox Empire.

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.

You shall become king—

Ruling over all “serpents” in the world…

Become the man who bears the brunt of dragonkind’s fear and hatred.

A modern era when humanity is threatened by attacks from giant dragons flying from beyond the sky.

Controlling “leviathans”—serpentine spiritual beings created through magic—humanity is locked in a protracted war of resistance against the dragons.

Fortunately, there exist witches known as “magi”—battle maidens of salvation who formed covenants with “serpents” in order to combat dragons.

Nicknamed Hal, the young man called Haruga Haruomi makes his living through facilitating the covenants of these girls.

At the (partially coercive) request of his childhood friend Asya, one of Europe’s top witches, Hal returns to Tokyo New Town after an absence of three years.

Accompanied by the beautiful Asya whose appearance rivaled a fairy’s, Hal is running all over the place to secure his base of operations and taking care of matters related to school transfer when the elite dragon Soth suddenly attacks—!?

Life has been breathed into a brand new myth between dragons and dragonslayers.

A grand opening to the “birth” of a top-class battle epic!

In the Sky Sword Continent there are thousands of sects and strong cultivators as common as trees. In order to prevent his older sister from being forcefully married off, Lu Xuan had no choice to but to unceasingly cultivate and enter a sect to ask for a favor. By chance, a sword-shaped crystal of mysterious origins entered into Lu Xuan’s body, containing countless top-class martial skills, powerful martial arts, and everything you could wish for! A martial legend starts here…

- Description from Novelupdates

Traveling to Blue Star, eighteen-year-olds in this world can enter the island world and become island owners after being tested.

Xu Chengfeng’s awakening talent ability “Life Activation”, even the island world can’t judge the level!

Then, his island came to life!

Others need a boat to cross the sea, and Xu Chengfeng’s island set sail directly!

Relying on the life activation technique, Xu Chengfeng pulled up the invincible army, accepted countless races, and ran across the seas!

- Description from novelbuddy