Zaregoto - Volume 5 Chapter 5

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.”....

Inside the dining room.

Fangzheng: Hello, I’m on a blind date.

Sister Yu: A blind date?

Fangzheng: To make a long story short, I know you are here to deal with your parents. As long as we make it clear, we can go back to our respective homes.

Sister Yu: Do you know who I am?

Fangzheng: I don’t know much, so what do you say? Continue to photograph or?

At this time, a waiter came in and bowed awkwardly to the two of them: I’m sorry sir, I made a mistake, this is not the room you are looking for! Your blind date is next door!

Fangzheng: ….

- Description from novelbuddy

A little ruffian who fought recklessly without any morals and bottomline accidentally time-traveled to parallel space and became a Key Case Investigation Team agent. The huge change in identity had him creating chaos in the police station. However, a strange miracle system helped him repeatedly solve mysterious cases, turning him into an impudent ruffian detective!