I Became the Little Demon in Leading Role's Family - Chapter 607 - 616: After the Divorce, She Lost Her Value

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 became a heroine who dies during the protagonist’s awakening event.

In Victorian England, occult practitioners and the Nightmen Police, who hunted occult practitioners, were at odds and engaged in a fight to the death. Legend has it that one of the occult practitioners was a mysterious merchant who ran the world’s largest underground black market in the occult arts, offering a variety of rare treasures. Word says that the Nightmen have a newly appointed young detective whose decisive actions have solved many cases, and occult practitioners are terror-stricken hearing his name.

Duan FeiZhou: Good, both are me.

He transmigrated to this era because he accidentally clicked on an email titled “Congratulations on your million dollar inheritance” and confusingly agreed to join the Nightmen’s side to fight against the occult practitioners.

Who knew that the next day he would inherit a mysterious inheritance from his uncle – the owner of the world’s most prominent black market of secret arts underground trading… This was a bit awkward.

Duan FeiZhou decided to stay away from the strife to avoid falling off the horse and became a salted fish.

On the one hand, crazy black market customers hope that the black market will close down as soon as possible. On the other hand, the Nightmen are negatively idle, hoping that he is quickly fired. However, the more he rushed customers, the more the business of the black market became red hot. The more negativity, the more he was promoted in the Nightmen.

Seeing that the double-sided was becoming a bigger hassle, he was afraid his mask would fall off..

The Scotland Yard’s NIghtmen Leader, code name Z, has white hair, blind eyes, mechanical prosthetics, metal spine, all from war damage; his hobby is hand-rolling cigars, and if he can not save the hostages, he will shoot them together with the criminals. His highest ideal in life is to exterminate all the occult practitioners in the world.

He thought he had a heart of gold with a painful past, but step by step, he was impressed and conquered by the new young Nightman… He also reformed him.

Until one day, he learned that the young man who tugged at his heartstrings was his lifelong enemy – the owner of the world’s largest underground black market for secret arts.

Z: Oh well.

- Description from Novelupdates