Dragon King’s Son-In-Law - Chapter 774 - Becoming a Sage!!

An earthquake, another world, and a tentacle monster in his basement claiming to be his wife are just the beginning of a chaotic new life for Nick. He has new, dangerous, and exciting neighbors to get along with, people who want to kill him just for existing, and monsters with a taste for blood.But he's going to do his best to get to the bottom of everything and maybe even find a way back home. Even if he doesn't, he's at least not alone, for better or for worse.

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.

God: I shall bestow the Saintess upon you.
Pope: W- wait a moment! This is a boy!
God: That is the Saintess.
Pope: ??????

And just like that, the Saintess was raised by the church for fifteen years without any questions asked…

- Description from Novelupdates

The second Ye Lulu transmigrates, she gives birth to three children on the spot.