I Reincarnated as an Extra in a Reverse Harem World - Chapter 74: Thalessia Vire Aelinhart

After traveling through time and space and becoming the younger brother of Uchiha Fugaku, Uchiha Yuto felt very panicked! He was preparing to practice hard to become the God of the Ninja World and suppress everyone, but after graduating from the Ninja Academy, he suddenly discovered that he had another path to take!“Itachi, don’t be a ninja; be a prodigal son! Uncle will give you money. The more you spend, the more popular you will be.”Being a ninja can't save the Uchiha! — Uchiha YutoThe more money Uchiha Yuto makes, the stronger his abilities will become!

This is a world shrouded in darkness, and the pervasive black mist erodes all living beings.

Only fire can dispel the darkness and protect mankind.

But the firewood will eventually run out, the fire will eventually go out, and humanity will eventually perish.

until Rhodes came.

- Description from novelbuddy

Special police officer Li Yu was reborn on the body of a little girl who was abused to death by her fiance’s family in Dayong Dynasty after saving people and sacrificed. Special police officer Li Yu was reborn as Li Yu in ancient times.

In my hometown, the former fiance’s family took back the property left by the original owner’s father, smashed and countered the murders of the Zhang family again and again, and rescued the scholar in the next village when he went hunting in the mountains.

When the wind and water came up, the sudden locust plague was followed by a disaster of war…

- Description from novelbuddy

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.