The Demonic King Chases His Wife: The Rebellious Good-for-Nothing Miss - Chapter 1901 - Entering the City 4

Mimizuku, a small girl with chains on her wrists and ankles and the numbers “332” branded onto her forehead, wanders into the Forest of Night seeking to be eaten by a monster. However, when the ruler of the monsters, the mysterious and beautiful “King of Night,” refuses to eat her, she tries to formulate a way to convince him otherwise.

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.

Born crippled with a rare disease, abandoned by his indifferent father, and hated to the core by his half-siblings, Xylen’s life was nothing but a tragedy.His mother died searching for a cure, and the only person who ever cared for him was cruelly taken away.Betrayed. Schemed against. Left with no way out.Lured into playing Fallen Realm Online with the promise of earning money for treatment, he fought desperately, doing nothing but living in the game and failing over and over again—only to be killed by his half-siblings right before completing a crucial quest. His reward stolen. His last hope shattered.With nothing left to lose, he ended his own life in the real world… only to wake up on the day the game was released.Armed with future knowledge, Xylen vows to seize this second chance. He will become stronger. He will protect the only person who ever mattered. And he will make those who wronged him pay.But fate had other plans.Instead of a normal start, he is forced into a demon fief as a baron—with an uncle who wants him dead. If he fails to kill his uncle and defend his land, his character will die, and he will be permanently banned. Worse, he is given a race despised by both NPCs and players—and given a class that should not exist.A mystery, fearsome, and despised character to the world. Feared by gods and demons alike. A walking catastrophe in the making.Yet, the more he learns about his new power, the more he realizes…This is no curse. This is his greatest weapon.And when the world finally learns the truth about Fallen Realm Online?Xylenia will be the name that shakes reality itself.