Shock! The Spell Is In English! - Chapter 3: Body-carrying Carriage

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.

The old man pointed to the flower-like woman and said, “Call her mother from now on.” He then pointed to a flower-bud-like girl and said, “This is your sister.”

My younger sister was not cute.

She was arrogant, taciturn and weird, but she knew how to please our parents.

She was two-faced and deceitful, but it seemed like she only treated me that way.

I cared for her, tried to please her as much as I can, but she still disliked me.

Until one day, I found out her secret, our relationship began to get a little bit weird…

- Description from Novelupdates

Enter a world of superhuman abilities and mysterious organizations as you follow the story of Jiang Bei, the enigmatic founder of the Infinite Alliance.With the power to extinguish stars and melt anything in his path, he is hailed as a god among men and the torch of the Dark Era.But what secrets lie behind his incredible powers, and what will he do to protect his legacy and extend his life?

Katherine Zara, a single middle aged office worker, went about her day as she always had; wake up, go to work, come home and read or play games. However, today would be different. Before she left for work, her ex broke into her apartment and killed her.

When she woke up, she was given many choices. She could pick her new world, pick her starting point, and pick her system among many other things. And so Katherine decided to become a servant to a villainess.

Follow Katherine as she serves her petty, demanding mistress in a world of swords and magic.

Additional: The Female Lead (Katherine) will be submissive to her mistress, but will be cold towards others. I plan on having some action, but mainly this will be a story about Katherine serving her mistress and leveling up her system.