Mr. Rong’s Lovelorn Diary - Chapter 45: I saw you.

The bad news, at least for me, is that I died. The good news is that I was reincarnated into someone else's body who lives in a cult full of beautiful women... but this cult forbids love. Well, one can't have all the good things. I thought I was safe until the worst happened. A system appeared that told me that I would die if a girl didn't accept my confession within a month... I have to get out of that cult now.Every 10 days I upload 15 chapters at once on Patreon.

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.

I just want to be different, no one can guess what I want to do, the more mysterious the more powerful.

- Description from novelbuddy

In this world, there are those that are fortunate and those who are not.

Ethan Bellrose is neither; he is cursed. At nineteen, he has lived his entire life sheltered in his home as his fragile body blisters under sunlight, breaks under the slightest impact, and falls to any sickness.

However, the arrival of a world-changing digital service catches the hopeless young man’s eye: “Reincarnation Online”--a virtual reality experience that gives a new fantastical life to those who are unfulfilled with their current path.

For Ethan Bellrose, the choice is simple. Without hesitation, he orders the virtual reality headgear, choosing to abandon his current life and live forevermore in the world of fantasy, magic, and endless adventure–”Arcadius.”

Though what he finds is a world not full of leisure and trivial triumph, but a world just as alive and full of darkness, glory, and grandeur as Earth–if not greater.

Starting from square one as an infant, given a new name and family, this is the eventful life, full of dreadful lows and exhilarating highs, of “Emilio Dragonheart.”

[...Booting System…]

[Welcome to Reincarnation Online.]

[You will henceforth by the recipient of the Dragonheart System.]

[Please, enjoy your stay.]