Himitsu – Kuro no Chikai - Chapter 3, Part 3 – That Which Was Abandoned

Lu Mingshu had never believed in fate.

The world is about to be destroyed to make way for an interstellar transmission array formation. A young man journeys through the stars to save his home. A bloody fantasy adventure.

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.

27-year-old Hisha, transmigrates into the body of a thousand-year-old overpowered supreme overlord who had everything at his disposal, except one–worthy companions by his side.

Hence, a tournament was held to choose the best out of the most beautiful, unique and strong women across the land.

These women don't follow the rule of coexisting women in a harem, they fight for the right to bed their lord and would stop at nothing but to use every opportunity to seduce, and fight on his behalf just to get his attention and favor.

Hisha never liked such a barbaric method of getting a companion.

'Why choose a few, if you can have them all?'

'If he can't have them all, he would try to work out coexisting the strongest for his pleasure and benefit.'

He realizes his 'Desire System' levels him up with every adoration gotten from his harem. The stronger they get, the higher his level and hold in his world.

As he continues to break his limits with the help of his harem, he finds out there are others that threaten his rule and the balance of his land.

'Let the tournament begin!'