Gonna Be a Demon King! - Chapter 31: To Stagger a Colossus

I’ve reincarnated as the reverse harem game’s villainess, the one and only step-daughter of the Eckart duke family.

The young master of the Huo Family was well-known in the Rong City. Having been brought up in a military, political, and business family, he was decisive in dealing with businesses, yet sexually continent as it was said. Nevertheless, he happened to fall in love with an illegitimate daughter.

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.

Even the most capable people cannot escape calamity. Zhang Ping, who dreamed of becoming the world’s best, voluntarily enters the palace to become a eunuch before his father has to resort to plundering and crime.

How can a prince be so thin and bony, that was Zhang Ping’s first impression of Huangfu Jie.

The prince looks at the kneeling eunuch, the scars and wounds on his body not yet healing.

Zhang Ping’s eyes turn red—I curse your ancestors for eighteen generations!

He is just little uglier; weirder than normal people.

Are ugly people not human? I, Zhang Ping, swear to cultivate the world’s second best over here in the palace!

- Description from Novelupdates