Personal Meta Essence - Chapter 18: [Safety] In Your Hands...

Being given a chance and reincarnated is nice and all, yet why do I have to become that male friend who just watches the protagonist flirting with his harem?---World: Kaguya-sama: Love Is War - Hyouka ----

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.

"Who touched you?" he asked, his eyes brooding down at her and when she didn't answer, his voice thundered in the room, "WHO?"

I turned my assassin into my maid with the power of money! Money is all-powerful!

It was a world full of swords and magic; Lawrend was the son of the wealthiest merchant in town. Since the age of 7, he had been having dreams. A dream about a past life in a modern civilization where monsters are nonexistent, and humans dominate the world. Lawrend saw Iron birds, Magical bricks that display moving paintings, Thunder wielding, and many more.

There was a scene in one of the dreams that made Lawrend’s heart beat fast. A row of a dozen maids bowing in front of him. Each dressed in a french maid outfit.

Something awakened inside Lawrend when he had that dream. A fervent desire to have his very own Maid Harem!