MTL - My Koi Sister is Three and a Half Years Old - Chapter 22 The Yan family's children are all bold

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.

SLASH!(So this is death?!!)I, Elysia, found myself dead before even reaching the Demon King's lair, and our Hero Party was completely annihilated.And this was done by none other than a fellow human—my former classmate.He had been mostly invisible during our time at the academy, but then he started committing one crime after another until he became a lackey of the Demon King.Who would have thought that the strongest party of humanity would be wiped out by humanity’s traitors?(If I could go back to the past, I swear I will kill you!)Just when I thought I could finally pass on, I opened my eyes.Five years back, when I first enrolled at Arcadia Academy.And there he was, the traitorous bastard of humanity...****“Huh? Where am I?”One day, I opened my eyes to find myself in an unfamiliar place and came to realize this was the world within the novel Savior's Dawn that I had read.Everything seemed to be proceeding the same as in the novel—except for one thing.The main heroine is glaring at me as though she wants to kill me.Could I survive with the main heroine after my life?

Within the red tent, under the passionate eyes of the man on top, she was forced to make love and three thousand black strands turned to white.

In this world, human are in peril. 72 Obelisks suddenly appeared out of nowhere, infecting the world with Monsters. Amongst this chaos, people look for hope.

A man named Basil Pacifer is the humanity's hope. He is the strongest Mage alive at that point. Sadly, he believes in no man, and he always moves alone.

...

Basil observes the unfolding scene bitterly. He is aware of his impending doom, however he has no grudge. He has lived long enough to achieve things people can only dream about.

Looking back to his past, he realized his life is nothing more than a sad story.

Closing his eyes, he accepted his end — or so he thought.

...

”Look at me! What do you see?“

”Regrets.“

”Don't you want to undo it?“

”Tell me what the offer is.“

Thus, Basil Pacifer returned to the past, being his younger self once again. Of course, he returned back with something.

...

[Ding!]

[Guide to Omniscience is successfully merged with The Chosen One]

[Analyzing The Chosen One's mental capability...]

[Analyzation Complete!]

[Result: The Chosen One is retarded]

[Initiate Brain Configuration!]

No matter how useless the golden finger he received seems, he will reach a higher height than his last life. This time, he will completely erase any regrets he has!