Very Pure and Ambiguous: The Prequel - VPAATP - V4C149 – Something’s Wrong

Xia Yuqing is a shut-in+fujoshi from the 21st century. After an accident, she transmigrates into the body of a young princess forced into a political marriage to another country.

“W-where is all this blood coming from? Is this– Is this nose blood? AH, YOUR HIGHNESS! A-are you alright? What? No! You mustn’t! Princess Xia, please, come back!”

“… I… need… to… see…”

The aide could only helplessly look on as Princess Xia Yuqing crawled towards the emperor’s quarters, leaving a trail of blood in her wake.

Fujoshi: a term for a woman who enjoys reading about relationships between men.

- Description from Novelupdates

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.

I just want to be different, no one can guess what I want to do, the more mysterious the more powerful.

- Description from novelbuddy

Global mutation brings the game to reality, and humans enter the era of universal job transfer!Damien Blackwell starts out as a standard villain, born into an ambitious villain family, willing to do anything to achieve his goals, even if it means subverting the entire empire!He begins by hunting down the Child of Fortune, ruining his future, cheating on his beloved, killing his parents, and forging a blood feud.The Child of Fortune swears to take revenge!But Damien Blackwell doesn't care at all.Who says that villains will eventually be defeated by justice?Who says that villains must inevitably become stepping stones for the Child of Fortune?In this life, Damien Blackwell plans to step on the bones of the Child of Fortune as a villain, climbing step by step to the top to become the ultimate supreme!He aims to craft a perfect villainous life.