One Piece: I'm Destined to Be the Son-in-Law King! - Chapter 198: An Unprecedented Crisis

Reborn in 1992, he supported the college student wife Ben and Shuo to study in a row, but she was not allowed to* after ten years of marriage, and she was scolded for peeking when she was washing her hair!

“You’re my wife, what’s up with you washing your hair!?”

“Sneak peek?! You gave me that stealing word!”

“divorce!”

He Hongchang slammed the door into anger and slammed away, but he plunged into the mouth of the hurricane where pigs can take off, and became a trend-setter of the times!

- Description from novelbuddy

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.

The course of commitments never did run smooth.

Looking at the system’s golden fingers after crossing through it, what can Susie do? Su Shi is also very desperate!

However, the next scene made him stunned.
A popular female star, suddenly confessed to him?
The sister of the relationship is like a fire, actually cooking for him?
Never look at a man’s cold and proud school flower, do you want to live in his home as a fiancee?

Did this group of girls brains? I don’t know them at all! ! !
of course not! It is because they have acquired the subsystem of Su Shi’s protagonist system, and they have a main task that they can’t think of!
– Become a girlfriend of Su Shi!

- Description from uukanshu translation