MTL - To Hold One’s Joy - Chapter 521 Things are different

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.

I was reincarnated as the supporting character of a novel. As a wingwoman in a depressing romance novel titled at that. Romance is out of the question, and the future of my family is ominous because of debt. I was going to become a civil servant to gain some of the splendor I never got in my last life…but the male love interests are acting kind of strange?! “Just think about it, does Shushu look like someone who would blush and act shy?” “Wow…….that would be great.” Cory said as he stared at Hylli in a daze, and Yves frowned and whispered to himself. “Should I just kidnap her…….” Swan wrapped his face with both of his hands and stayed quiet. His face turned bright red. The blush turned his ears red. Why are you guys fooling around, you’re supposed to be obsessing over the heroine. The story of Shuraina West, Shushu’s reverse harem academy survival. Note: Ojakgyo means wingman/woman!

– The planet [Earth] has entered the abnormal state [Apocalypse].

– You have failed in saving the Earth. The Authority, [Vintage Clock (EX)] rewinds the world’s time.

For Yu Jitae, it was a message he had seen many times.

It was tiresome.

It would have been great had he died with everyone else.

But he couldn’t, for his authorities that made him the strongest existence, brought him back in time whenever he did.

And even with his strength, he couldn’t protect the broad earth against the maddened dragons.

– The world’s time will soon begin.

As the clock resumed ticking in the direction it should, his 7th iteration came to a start.

Fortunately, he finally had a gist.

I freed the Slaves, but for some reason, they keep chasing after me.