Seirei Tsukai no Blade Dance - Volume 16, Chapter 11 - Ghosts of the Demon Capital

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.

Reincarnated in a magical world with INTERNET POWER?Nolan, a failed teacher, dies and wakes up in a ruined fantasy world—in the body of a Mana Specialist—a magic instructor who helps wizards and knights control the dangerous, corrupted mana flowing through their realm.The problem?The body’s former owner made a deadly pact with a succubus and was hunted by his noble family. Worse still, Nolan doesn’t know a single thing about being a magic specialist that could’ve helped him tremendously in his troubled situation.Just when he thought all hope was lost, Nolan gains access to the Internet. Not just Earth’s version, but this magical world’s version too.Need a face slap? Buy an internet promo to gain access to the knowledge wherever he needs.Succubus problem and strengthening up? Play inside the game and get stronger in real life too.Sometimes, to solve magical problems, all you need to do is browse.

In the 21st century Earth gave Birth to greatest genius ever. A genius who Master myriad of arts. Medicine to Engineering. Mathematics to Micro Biology. Weapon Designing to Environmental control. Music to Painting. Dance to Martial arts. He mastered Everything.

Su An was thrown into a world of quick transmigration by his suitor, who attempts to approach him with a different identity.

Hidden dangers can not be prevented, but fortunately, with sweet words and beauty, Su An has won the love of the big bosses from each world.

An indifferent painter suffering from mental illness, a flirtatious bandit young master from a wealthy family, a demon monk with powerful martial arts skills…

To Su An’s surprise: Every big boss is poking my appetite!

The big bosses who got hooked up: …

They all gave a meaningful smile.

- Description from Novelupdates