Demon King: Hero, don't run away! - Chapter 6 - : The Seven-Leaf Clover

Bai Aoxue, the best mercenary in the 21st century, is accidentally sent back to the Chengxi Dynasty in Great Continent due to an explosion in her mission, and trapped in the first daughter of Prime Minister. After her rebirth, she is set up by her father to marry the 5th prince Jun Yeyan who wears a mask all day long.
In the face of bloodthirsty enemies, discord between brothers, collusion among courtiers and invasion of enemy state, can Bai and Jun resolve the crises? What will happen to their political marriage? How will the fierce battle for the throne end?
With many twists and turns, the book brings you to experience palace revolution, love and hatred thousands of years ago.

- Description from Novelupdates

Knox is an omega – poor, orphaned, weak, and bullied. He was the unluckiest human being alive – according to his own.Burdened by debt, he has no choice but to stop school and work to pay off his loans all the while hiding the truth and pretending as a beta to save himself from harassment. He accepted all legal jobs he could get to make ends meet.Including a contractual relationship with an alpha who’s suffering from a pheromone disability. He gets paid – enough to free him from all of his debts. All he has to do is help the alpha stabilize his pheromone…not until that night happens…The contract was breached. Knox has to pay the price. Afraid of his circumstances, he ran away.Years later, Knox became a capable man. He has a nice job and a kind boss. When his boss got invited to an engagement party, as his secretary, Knox had to come with him. However, he was shocked to find out that the man to be engaged was none other than the spitting image of his son!How will Knox keep the truth from him, when after their eyes met at the party, the alpha had already marked him as his property, claiming him as the payment of the contract he breached?Will Knox hide and run away again? Or will he choose to pay off the debt to be free? Will he be able to push away the alpha whose vices are hidden behind his attractive mask or will Knox abandon his virtues and embrace the dangerous father of his son?

He was once a great Immortal, but his attempt to ascend the Nine Heavens ended in failure. Reincarnated on the Blue Star, as he opened his eyes, he found himself with an adorable daughter. And a stunningly beautiful wife?“Daddy, can you cast a spell for me?”“I could even pluck the stars from the sky for 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.