The Hero King, Reincarnate to Master the Art of War ~And Thus, I Became The Strongest Knight Disciple (♀) in The World~ - Chapter 415: 16 Year Old Inglis and the Highland on Distance Sea (24)

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.

Transmigrated into a novel after her death, Su Jin has an engagement with Lu Xi, the legendary and unrivaled male protagonist, that was arranged between their families. After the revelation of her identity as the adopted daughter swapped at birth, she had no right to the engagement; that belonged to her sister, the female protagonist. In fear of interfering with the novel’s ending, she avoids him… But why is he ignoring the female protagonist and chasing her instead!

The Perfect Fiancé Code:

1. Support his fiancée

2. Unconditionally support his fiancée

3. Protect his fiancée unconditionally regardless of who or whom is present

Lu Xi felt that he should be able to accomplish this.

Su Jin: QAQ, please don’t do this…. I’m supposed to be the cannon fodder sultry ex-fiancée that you were going to dispose of!

Lu Xi: I have always been waiting for the moment that the 22-year-old Su Jin, you, would finally open her eyes.

- Description from Novelupdates

“I believe that if you have a problem, we just need to solve it with firepower. If the problem isn't solved by then, it just means we weren't using enough firepower.”In a world of swords and magic, Lucen Thornehart, the eldest son of the Iron Duke, was considered the shame of the noble knight bloodline. No talent, weak, and worthless.Until one day, when a fever awoke his previous life's memories and the knowledge of the class from an old game he used to play, Gun Mage.More than just guns, he creates weapons that have never been created in this life and the last.A sword that heats up, turns crimson, and could melt metal.A rune-engraved gun that mages use to amplify their spells.A giant sword that you would only once see in a video game, which makes an explosion every time it hits an enemy.A gun that is powered by mana and shoots out condensed amounts of mana.Airships, steam trains, and boats.Lucen Thornehart isn’t here to play fair. He’s here to redefine warfare, with overwhelming firepower.

Lukas was forced out of high school before he could undergo the Awakening Process. His dreams of starting a new life by becoming an Awakened were shattered.Becoming an Awakened with supernatural powers meant being bestowed with riches and all the resources needed to fight off the invading hordes of demonic beasts.Lukas received the Slaughter System instead. With every kill, he was able to grow stronger and gain new abilities.[Ding!][Congratulations on Host’s first slaughter.][Current Slaughter Points: 1/500][Host Level: 1][Please Select New Ability]Soon, he was able to fighting off demonic beasts invading and move up the ranks.