Reincarnated as the Villainess's Unlucky Bodyguard - Chapter 122: Blades and Shadows

In a Fantasy world in which a young girl with the Divine Protection of the Hero battles against the Demon Lord. In that world, Red, the elder brother of that young girl Hero, possessing the Divine Protection of the Guide which only grants a high initial level, fought in the initial party of the Hero.

Rise Lee, a well-known A-rank esper in the federation. He was even ranked as one of the strongest among the A-ranks and recognized as one of the hopes for humanity. However, he wasn't only famous because of his prowess or his attractive appearance; Rise was more infamous because of his terrible personality. He was called a villain by most guides and espers for a reason.And who would guess that Rise Lee was really a villain, in a literal sense? The terrible truth then unfolded to him. He, Rise Lee, is one of the main villains of the novel. Rise Lee spat out a mouthful of curses and swore that if he had a second chance, he would mess up this damn novel until everyone went down with him. If the author was in front of him, he too would be destroyed with him! And a second chance did come! Rise Lee, the villain, woke up five years before the main storyline! Heh. So what if he was a villain destined to die? That protagonist who killed him, and the author... He would screw them over. Being a villain, be damned. In this rebirth, he would take and mess up everything. What did you say? The protagonist’s love life? Heh. That too. Rise would take his lover. The male lead... will be his.

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.

Entering the mortal world for a hundred generations, do not compete for the youth of one life, but only for the day and night of a hundred generations.

Seeking immortals in the world of mortals.

My name is Li Qing. I have escaped from the mortal world in the third life, entered the Tao in the ninth life, and become immortal in the hundredth life.

(longevity stream, non-simulator, non-reincarnation rebirth)

(Bai Shi Shou Yuan, One Life Life)

- Description from novelbuddy