Marked Ones: Advent of the Demon Prince - Chapter 339: Terror in the Dark [Part 1]

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.

[Invincible, showoff, face-slapping, feelgood]“Who is richer? Sorry, Every watch I have is worth billions. Money is just a number to me!”“Wanna fight? Fine, I won't even use my hands and feet. I've never lost a fight in my life!”“You like me? Sorry, even a cruise ship is not big enough to hold all the women I have. Haven't you seen the princess of Anenida lining up for me?”With the invincible system, everything can be easily accomplished.Please don't show off in front of me. I have a nickname called Face-slapping Zhang!

Alexander was the greatest tyrant in history. His cruel, brutal and vicious reign struck fear in his enemies and allies alike. But that all ended when he was betrayed by his own people and beheaded by his archrival. As Alexander’s consciousness faded away all he could think of is all the faults he made, how he could have avoided them, how unlucky he had been, and his wrath and unwillingness to die at the hands of the man he hated most! But unexpectedly he was given not only the answers to these questions, but also a second chance to right all his many wrongs.

Have you ever thought a monster that has a job of a summoner and a tamer

what should it call itself Monster Summoner? Monster Tamer? but he itself was a monster too

Watch as our mc travels the world as an reincarnated human who turn into a monster