Grind to Greatness: The Barista System - Chapter 36 - 35 – Seeds of Change

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.

[Mature Content!]In the heart of a bustling metropolis where ambition and dreams collide, Ella, a talented yet struggling artist, finds herself facing a crushing blow. Her world shatters as her ex-boyfriend exchanges vows with her former best friend, a betrayal that leaves her feeling humiliated and lost.Desperate for a change, an escape from her heartache, she impulsively agrees to a marriage of convenience with Damien Stone, a mysterious and enigmatic billionaire CEO. Damien, needing a temporary wife to appease his demanding board of directors and secure his position, sees the arrangement as mutually beneficial. As they enter this calculated agreement, both with their own hidden agendas, an unexpected spark ignites between them.Amidst the carefully constructed facade of their marriage, a genuine attraction blossoms, challenging their preconceived notions and altering the course of their lives in ways they never imagined.

A world where waves of monsters descend every night...A world where only the strong can survive.Axel, a burned-out man from modern Earth, wakes up in a desolate wasteland with nothing but a strange “Harem Settlement System” with him.Given the power to build, command, and grow stronger, he sets off to carve out a safe haven in this broken world. But as his settlement grows, so does the number of beautiful and deadly women drawn under his blanket-ahem!-banner.Witness Axel's journey, rising to to the peak. From a simple, lone survivor to becoming the Wasteland Overlord. With the help of the loyal, dangerous, and irresistible thirsty harem girls!

A young man who had longed for stories of good and evil since childhood lost his life in a tragic accident and was reincarnated as a boy named Chrono Mak in another world.

He learned that in this other world, there is magic and witchcraft, and depending on how you train them, you can become as strong as you want to be, so he decided to become the strongest demon king in order to recreate the story of justice and evil he once dreamed of.