Richest Man: It All Started With My Rebate System - Chapter 64: The Get Together

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.

Yuzuki thought it was just another pastime from his casework, proofreading a half-finished fantasy webnovel. But when he woke up the next day, he was no longer in his world. He was inside the story… as a disposable extra.The world he now walks is beautiful, brutal, and broken. Its plot is incomplete. And looming over it all is a calamity so catastrophic that even the protagonist would have failed to stop it. Driven only by his cunning and spite towards this twisted fate, his only choice is to stake his existence in a world on the verge of collapse. But how long can a nameless extra outwit the fate of an unfinished novel? How is he going to survive in this ruined world?If the story dies, so does he.“Well, curse the protagonist. Why would I gamble my life on some self-righteous fool who’s just doomed to fall anyway?”#Academy#WeakToStrongMCNo Harem!

Time flies quickly; may you enjoy a cup of drink.I know not the height of the green mountain, nor the depth of the earth.Only watching as the seasons change, that it took people's lives.

Traversing into the world of “My Hero Academia”, the awakened personality is actually a stand-in [World].

In the face of the invitation from All Might, Wu An said: “I have no interest in heroes, I just pursue power, and I have nothing to do with women.”

Facing the provocation from ALL.FOR.ONE, Wu An opened his arms and summoned his stand-in.

“THE. WORLD! Time! Stop!”…

- Description from novelbuddy