The Return of the Crazy Demon - Chapter 40: Be Nice When He Smiles At You.

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.

[Warning: Mature Content and a ruthless, villainous, badass mc!]Kael Draven was once the feared leader of an underground mafia empire. A shadow ruler who pulled the strings behind the scenes.But power comes at a price. Kael learned that the hard way when a bullet pierced his ear, and his trusted ally betrayed him, bringing his life to an end.Bang!As his empire crumbled and his body hit the cold floor, all he could think was, ‘What a pathetic way to go.’Instead of hell, Kael woke up in a far more dangerous world, with a body stronger than ever—youthful, shredded, with muscles for days and an ego that could crush mountains.His title? Master of the Crimson Maw.He now led a bandit group that had angered a mysterious force and been wiped out—except for one survivor: a strong, silent gladiatrix who wanted nothing to do with him.To make things even more interesting, his body bore a glowing tattoo that whispered in his mind: “Bond. Through body. Through soul.”But Kael wasn’t one to back down. He didn’t like losing.So what if his base was a dilapidated shack? So what if his army was just one extremely voluptuous warrior?Kael wasn’t here to play small. He was going to turn this ragtag bandit group into a force feared by all, with a harem of deadly beauties who would bow to no one but him!Welcome to the Crimson Maw. Where the training is brutal, the beauties are overpowered, and the only thing more dangerous than an enemy is the bandit king himself.Let the grind begin!

The grand master of Shape-Will Fist, Ning Wufeng, was brought to the Divine Land Continent by a mysterious scroll. In this world, he was an abandoned child and appointed by his family as inferior leader of a small fishing village because he was unable to open up his Spirits Aperture and begin his cultivation.

However, he seemed destined to open up his abandoned with the memories of previous life integrating into his mind. And the scroll guided Ning Wufeng into a vast mysterious hidden world where he was bestowed divine weapons and acquired supreme skills of cultivation.

Deafening thunder indicated the immense changes in the movement of winds and clouds. In a world where people worshiped martial arts, how could the teenage loser be the master of his own destiny? How could he wield his power to control the world, making gods and demons tremble with fear?

- Description from Novelupdates

[mafia, crazy love, abusive love]She was reborn, returned to the age of 18, when she already possessed a colossal fortune. In the previous life, she was executed on the street and died tragically merely due to a dangerous man she'd encountered once.After being reborn, she decided to change her fate. As she pondered how to avoid him, she unexpectedly discovered his name on the list of beneficiaries of the charity.“Can I kill someone?” She asked her assistant.“No. The law binds you!”So, to survive in this life, she tricked him back home. Initially, she believed it to be a means of repayment.Until one day, she felt his gaze become terrifying. She saved him, but accidentally led him down a more terrifying path. Everything had spiraled out of control…When they meet again, he is already a terrifying demon. With blood on his face, he forced her into a corner and said, “Be my mistress, or let me be yours.”She threatened him with a knife, but he laughed even more brightly and held her hand, saying, “You're afraid of me? Ok, I'll teach you how to hurt me the most.” And he guided her hand to hurt himself.She suddenly understood that she should have left him alone. He was injured, bleeding, but still laughing.She said lovingly, “I am indeed afraid, but I don't deny that I love you...”