It's Actually Not Easy Wanting to be a Supporting Male Lead - Chapter 12 part10

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.

She is intelligent, beautiful, calm, and professional. As the youngest chief forensic investigator for the past few years, her future was very bright. All of this, however, changed with a bizarre time-travel.

Li Xuehao found a secret of monasticism in the cover of the genealogy. After spending ten years, he finally succeeded in building the foundation. Unexpectedly, he was eager to get rid of the evil spirits. After his death, he was born again in Yokohama, Japan, and was attached to Sakura, Tsurumi. The story of the high school student Gao Zhonghao in the college, the story begins here…

- Description from Shubaow (Translated)

In a world where magic is a science, Siobhan is a genius.But even geniuses need schooling.When Siobhan stumbled into the theft of a priceless magical book, she thought her dreams of becoming the world's most powerful sorcerer were destroyed.But then a mysterious spell changed her life forever...Siobhan is now wearing the body of a strange man and has a new identity—Sebastien. With a new chance for a new start, she allies herself with a local gang—secretly a revolutionary party funding itself through crime. Now, she is bound by vow to repay them in magic and favors. But as Sebastien's reputation begins to bloom, and Siobhan's old enemies still lurk in the shadows, she quickly realizes that the secrets of this world are deeper and darker than she ever could have imagined.Forced to juggle the two sides of her double life, Siobhan is determined to uncover the truth and take control of the name they gave her - The Raven Queen.