Demon Slayer : The Silent Journey - Chapter 9: Rengoku Kyojiro!!

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.

This is a very serious Xianxia book, but why the introduction I always want to describe it as: My second child is a giant, and there will be something going on in the future, and so on.

In short, you will understand after reading it, this is really not the YY of male species, what is missing, what is missing, etc. I am telling the truth.

- Description from novelbuddy

A thousand-year dynasty would inevitably face decay, and a hundred-year noble family would eventually return to dust.What in this world could last forever?Was it an Immortal Body, tempered a thousand times, or the Martial Arts will, in Heart Unity with heaven and earth?Chen Mu came to this world, his sword in hand, and when he turned back at dusk, countless heroes and millennium-old Demons had all turned to dust, leaving only one person on the road paved with yellow sand.

In a not-so-distant future, Earth is thrown into chaos by a weird alien ship that crashes and starts leaking spiritual energy all over the place. This energy messes with the planet’s ecosystem, making everything mutate—animals, plants, even people. It’s like nature’s gone wild, with some folks getting crazy supernatural powers while others struggle to survive against mutated creatures and power-hungry groups trying to take control.In the middle of all this craziness, Amira Hailen—a tough-as-nails ex-special forces assassin with a complicated past—gets a second shot at life. Thanks to a mysterious ally’s Mental Transference powers, she’s sent back in time, waking up with the ability to control ice. Determined to keep humanity afloat, she gathers her old crew and turns them into a reliable team amid all the chaos.Meanwhile, Aiden Emberstorm—a fiery elite operative—gets fed up with the government’s weak response to the crisis. With his own fire powers blazing, he ditches the bureaucracy and teams up with his battalion to protect innocent lives. He becomes a symbol of resistance, taking on mutated beasts and rogue factions while trying to restore some order.When Amira and Aiden cross paths, it’s not exactly love at first sight. Their icy and fiery personalities clash, but they can’t deny the need to join forces. They both want the same thing: a sanctuary where survivors can be safe. So, they decide to work together, hatching a plan to take down the alien ship before it can call in reinforcements for a full-scale invasion.Amid epic battles, unexpected alliances, and a budding romance, Amira and Aiden must face both their inner demons and the alien threat. It’s a fight for survival in a world that’s gone wild, with everything at stake—including their own hearts.