MTL - Naruto: Ten-year-old Kaleidoscope, Opening Betrayal Konoha - Chapter 568

Demons are rampant, the court is corrupt, the human race is declining, demons are rampant, and the world is treacherous and haunted.

Martial arts masters are just more delicious blood food in front of monsters.

There has never been a savior in this world!

My name is Jiang Heng, and I am the one who runs amok!

- Description from novelbuddy

During his patrol, Ji Xiu Yun, a marshal of the Empire, was ambushed and went missing. When he returned, there was a pure white creature crouching on his army cap.

Through genetic testing, it was determined that this cute and delicate little fellow was a creature that had faded away with the mother planet of humans 2000 years ago——a cat.

The last cat in the universe!

The people of the Empire were frenzied!

- Description from Novelupdates

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.

At some point in the 21st century, the Christian God stopped listening to the prayers of humanity. Monsters with colossal strength and endurance began to emerge and humanity entered its darkest period.