MTL - The Dragon Princess Who Traveled Through Another World - Chapter 189 time valley

Three Days of Happiness is a novel by Sugaru Miaki, also known as Fafoo. It’s a rewritten version of the story originally posted to 2ch.

The premise of the story revolves around a shop where one can sell away the remaining years of their life, and the consequences of doing so.

“I Say A Little Prayer” is a short related story which was posted along with the novel’s release. It spoils some things about the main story, but nothing major.

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 boy that was imprisoned for millions of years has regained a mortal body.

He became a disciple of the declining Cleansing Incense Ancient Sect where its patriarch used to be his disciple. Now he will bring this sect back to its former glory.

This is his journey to reach the apex and take revenge on those who had imprisoned him.

This is his story of meeting old friends and making new companions.

This is his path of traversing the Nine Worlds and becoming the next ruler of the Heavens.

Several milennias have passed and the golden age of experts have passed. A master whose disciples once were the most exalted Immortals among the 9 worlds have all left him. With his mortal body, mortal physique and mortal life wheel. . . he shall sweep the 9 worlds and take what is rightfully his.