This Japanese Monogatari Isn't Lame - Chapter 35. Reasoning, Not Fighting

For twenty years since his soul had transmigrated, Bailuo thought this was an ordinary world, until one day, a black leather book appeared in his mind.“Is there magic in this world?”Facing Bailuo’s question, his uncle remained unwavering as he said, “No.”“But there are miracles.”“What are miracles?”“A sword that can release flames, a pot that can pour out gold, a beautiful girl grown from a fruit.”The uncle said, “Controlling the mist, bringing the storm, commanding the thunder.”“Magic!”Bailuo raised his hand and pointed, “This is definitely magic!”“No.”His uncle said, “These are truly miracles.”Years later, when Bailuo looked upon the nation he had built with his own hands, that magnificent and majestic sight, he agreed with what his uncle had said all those years ago, “This is a miracle…”

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.

Originally born from a wealthy family, she ends up leading a vagrant life for fifteen years. However, when she is eventually found by her family, she falls into another devious plot and eventually dies tragically.

Fifteen years after her rebirth, ravenously raging for revenge, she tears down the hypocritical mask of the foster daughter who had taken her place, and reduces her greedy stepmother and stepsister back to their original sorry states.

To the jerk’s profession of his deep love for her, she only has one thing to say, “Get the hell out of my life. The love you speak of humiliates love!”

Regardless of the appearances of you monsters, I’ll take in it my stride with my capability, building a business dynasty of my own, sitting in the depths of my riches, bathing in the glistening limelight of the world.

A certain rich empire’s CEO: “Don’t mind me. I’m just leaving my mark here to declaring my possession rights; I’ll wait patiently for you to grow up!” The queen’s mighty return with commercial warfare fully within her grasp, she navigates the power struggles with skill and verve. When it comes to scheming conspiracies, all she has to say is, “Who are you again? Don’t even bother!”

- Description from Novelupdates

Qi Condensation. Foundation Establishment. Core Formation. In the current world, only these three realms are known to be achievable. Nascent Soul is but a legend and the realms above it lost to the the long river of time. The modern era is known as Cultivation Civilization, a balance of power and civility, excess and moderation. While cultivation remains a secret practice, it has long since exposed itself to the mundane world, quietly intertwined with each facet of society. While the world appears to be at peace, what lies underneath is a conflict between human, cultivator, and demon, brewing for ages and waiting to implode. Yet in the wake of humanity’s rapid industrialization, qi—and consequently cultivation—is dying.