The General's Genius Daughter - Chapter 258 - Pain

Quinn Winter is a young man from another world. One day, he is suddenly chosen to become the new Demon King. But the Demon Kingdom is in big trouble – it's losing a terrible war against the human kingdom called Gran'le.To help his people, Quinn comes up with a risky plan. He will sneak into Gran'le and learn their secrets. But things don’t go as planned. A powerful noble sponsors him, and he ends up joining Heavenward Academy, the top school for training future heroes.At the Academy, there's a big challenge called the Selection. The best students become Paladins – magic knights who fight demons. Quinn doesn’t want to become a Paladin. He is a demon king! But now, he’s stuck in the Selection… and if he wins, he’ll become the very thing he’s supposed to destroy.He started the day badly. Now, things are getting even worse.

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.

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

Tiara was killed in the real world and then reincarnated to live in the body of a noblewoman in the novel she read named Claudia Ambelynn. When she lived in the novel world, she was reunited with the main protagonist who was her husband who was killed in the real world. In addition, she also met the murderer in the novel world and also played the role of the main protagonist's older brother who was known as the most cruel character. It was not that easy for Tiara to live in the novel world written by her husband. She had to carry out a mission that she had to conquer the heart of the antagonist, Duke Harry, in order to return to the real world. This made Tiara think, if she lived in Claudia's body and married Harry, then she could take revenge on the murderer who killed her husband in the real world. The way to do that, she would try everything so that Harry would really fall in love with her. She was forced to cancel her engagement with Duke Harris in order to take revenge on Duke Harry. How did Claudia succeed in conquering Duke Harry's heart?