Hikaru ga Chikyuu ni Itakoro…… - Volume 4, Chapter 9 - The Moon Descends Gently

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.

Lin Qingge’s body was pathetically weak, so weak that just taking a few steps would make him gasp for breath. His own family treated him like he didn’t exist. His birth mother died when he was young and his father promptly remarried and knocked his stepmom up. His father didn’t like him, his stepmom looked askance at him and his step siblings coveted his position. Who told him to be the lawful eldest with inheritance rights?

When Lin Qingge was eighteen he came out of the closet, creating a huge rift between him and his family. It was all for that guy, Liu Yang. He’d whispered sweet nothings in his ear, saying things like he’d protect him and bs like that. Lin Qingge’s old man blew his top when he found out and promptly disowned him. That didn’t matter to Lin Qingge, he had Liu Yang afterall. He fully believed in that guys words and goodwill.

If only he wasn’t so stupid…

Ultimately Liu Yang was like a vampire sucking his wealth dry, leaving a husk behind. After pushing Liu Yang to a high position, Lin Qingge finally collapsed in his apartment. It was a sad sorry sight. Closing his eyes, he knew this was the end of him. Who knew he would wake up instead in a different time and a different place?

Eh? What’s this? Well fine! This time I’m gonna hug that brother’s thigh real tight and never let go!

- Description from Novelupdates

My name is Jiang Li, and upon traversing to this realm, I found no golden opportunities waiting for me. Through sheer effort, I cultivated my way up to the Great Completion Stage. Now, suddenly, a system appears, claiming it can help me turn the tables and transform me from a minor Qi Cultivation phase practitioner into the foremost figure in the cultivation world.

Dear system, you're a bit late to the party. I, Jiang Li, already stand as the Emperor of our era, revered across the nine provinces. I am already the number one in the Cultivation World.

……………………………………………………………

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A Pill Emperor of his generation was set up by a traitor.

Since then, the world lost a Qingyun Zi and gained an invincible silkpants.

Once again, walking the Great Dao of Alchemy.

How can I defy the heavens . . . with the medicine in my hands!

- Description from Novelupdates