Extra's Death: I Am the Son of Hades - Chapter 5: Training Arc

Upon awakening, the apocalypse's metaphysics master, Nan Li, found herself as the lost Sixth Miss of the Anyang Marquis ManorThinking it would be a story of abuse, she never expected all five of her brothers to dote on her one after another!Nan Li shouted, “Stop pampering me! In fact, I can do everything, from capturing ghosts, exterminating demons, divination, physiognomy, to healing and saving people. I'll lead the family to rise in power and wealth!”Accidentally saving the Ninth Prince, who held great power in the court, Nan Li found him renowned for his cold and unfeeling demeanor. However, he became utterly addicted to pampering her and refused to take other concubines.The scheming and malicious women were angry, shouting, “The prince lacks heirs, how can this be allowed?!”Nan Li pointed at the line of little ghost-catching disciples and said, “I'll cure your poor eyesight!”The Ninth Prince lifted her in his arms and said, “We have a bit of thin property that needs to be inherited, so we'll have a few more children.”Later on—Nan Li looked at the continuous immortal mountains and the room full of treasures, her mouth twitching, “I thought you had a throne to inherit, what's going on now?!”

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.

A story of time-travel. Sly and cunning, she unexpectedly became a sickly noble lady whose fiancé is merciless and demotes her to a lowly concubine. She sneers and bravely breaks off the engagement. To hell with scumbags, marry heirs to lords, blind the courts with her brilliance.