One Piece: Pirate King? I just want to kill all of you - Chapter 67: Hmm?! Another Master!

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.

Rhian Locke only wanted strength.To face the monster that slaughtered his parents while he watched, helpless.“I never asked to be your savior. So why should I care?”All he hoped for was to reach a decent rank, hunt that beast down, maybe become a monster hunter, and retire in peace.“I’m not a slave to the gods. I don’t exist to do their bidding.”But the world had made its decision long before he was born.“Patterns are meant to be broken.”------“Boy, I’ve bathed in the blood of your kind. I’ve crushed those stronger than you.”Lightning cracked across the sky. A hammer flew to the hand of a god.“I won’t let a deceiver’s spawn and a whore’s bastard son, stand before me and declare my end.”Rhian stepped forward, blood trailing from his mouth, eyes locked.“I’m not here to declare your end,” he said coldly. “I’m here to fulfill it.”....

A man was about to commit suicide and decided to search for a way to die on the internet, but then he found an odd site that asked a lot of questions and had a point based system that allows you to create skills for a character. He took interest in it, and when he was done setting his character, he was asked, “You will now be transported to a world with the settings you chose. Coming back is not possible. Do you still accept?” Without thinking much of it, he pressed YES and found himself in another world with the skills he chose to have.

“Stop crying. I’ll marry you. Calm down.”Cold. Emotionless.That is Duke Morvex, the monster duke whose half-blood lineage comes from the terrifying wolf demons.And I, Valerie Austin, wake up in the same bed as him, the ruthless duke who should never have touched me.But the biggest problem isn’t that forbidden night…It’s the truth everyone in the empire already knows:Duke Morvex is engaged and soon to be married.