Raidorl Seiken Senki - Chapter 13: Determination and Ambition.

The hearse with the weird odor slowed to a stop before the entrance. The sound of pebbles could be heard bouncing on the ceiling. There were footsteps coming from the corridor, and there seemed to be someone sawing next door. The door knob to the room rattled slightly, and the faucet in the bathroom kept dripping even though it had been screwed shut. There was a rubber ball that rolled on its own underneath the bed. Wet footsteps started to surface one after another on the floor.
At 3 am, Chen Ge held a cleaver in his hand as he hid beside the room heater. The call he was trying to make was finally answered. “Landlord, is this what you meant by ‘the house can be a little crowded at night’‽”

- Description from Novelupdates

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 female lead tormented scum without rest, and the male lead showered her with endless affection.Returning to the turning point of fate, she was determined to strike the supreme with her fists and kick the trash underfoot.Those who had once wronged her, deceived her, and taken advantage of her, brace yourselves for trembling!Watch him and her: not wasting their prime years, hand in hand, they compose a grand wedding!

+18 Warning Mature Content - Reader discretion advisedA wolfless ward and an illegitimate dragon prince must overcome immeasurable barriers to free themselves from the stigma they have been placed under.Abandoned as a child Lily Artemis Wolfman was taken in by the Royal Family of the Wolf Clan only to be treated like a slave, working her mercilessly night and day.When her wolf didn't appear, Lily used her only avenue to free herself on the day she became an adult.Finding a mate was the last thing Dimitri De Drago` wanted since his family was hell-bent on killing him, but when he came across a strange female amid a massacred village his dragon stirred for the first time at the sight of her.Turning her away only to find her again caused sparks to fly between the two like they never knew was possible. Facing fatal issues within his Clan, finding his mate came with serious consequences.They knew trouble would follow if they stayed together, but their souls demanded each other risking it all for the chance at happiness.Will their love remain strong through the trials and tribulations they face or will tradition and their families stand in their way of true happiness?