I Alone Level-Up (Web Novel KR) - Chapter 263: Side Story 20 - Twelve years later (2)

Read at least six chapters, then prepare to crave the rest.The main character will show up in Chapter Five, though I don't recommend skipping the first four chapters.-----The world was celebrating. The Demon King was dead, along with his Darkness Generals.Humans led the other races to war for subjugation. They killed all, and none were spared. However, thousands of years before this happened, a piece of history was altered by time itself. In fact, the Demon King didn't have four generals but only one, which he sealed and sent into eternal slumber. Just as he started to close his eyes, the chains locked away for eternity shattered into pieces.

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 person that Pei Zhen hates most in his life is the perfect Fu Sichen. Alas, life is full of surprises and unpredictability. One fine day, an accident turns Pei Zhen into Fu Sichen’s pet cat! As Fu Sichen’s pet cat, he makes a shocking discovery about his sworn enemy – a deep dark secret that the perfect Fu Sichen has kept hidden for years. Trapped in his cat body, Pei Zhen moves from one adventure into another while trying hard to find a way of turning back into his human self. When he finally does, the world as he once knew, has become a completely different place!

A demon phoenix cultivator died in the hands of his beloved and was merged with a young master with the same name. Their souls were fused and now, the new Feng Fei Yun is struggling to become stronger and survive in the human world.