The Sword Deity in Tokyo - Chapter 226: Kyoshin Meichi-Ryu

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.

99 is one, and nine refinements are returned to Xian.

A young town boy, stepping on Xiuxian Road, is not a family, no gold fingers, with his own determination and wisdom, the nine major cultivation system, the nine realms step by step to the peak, and finally ninety-nine one, the achievement of true immortal.

- Description from Uukanshu translation

One Piece World (Completed): On the eve of the summit, the Navy Headquarters urgently needs a large number of elite combat forces to deal with the Whitebeard Pirates that will attack the Navy Headquarters next.

At this time, Warring States thought of the man who once shined for a while.

“The former admiral, the man with the most potential to become a marshal!”

“He was with Roger, Whitebeard, on this sea.”

“But he was also the only general who made a big mistake and was erased by the navy.”

Recalling the past, Warring States fell into hesitation.

Whether to use him or not, this will make the Navy take great risks.

The World of Naruto (Hot Serial): Starting from becoming the younger brother of Golden Shining, starting from the night of the Nine Tails, subverting Konoha and subverting the ninja world.

Sarutobi Hiruzen: No one would have thought that the young man who had been mediocre for twenty years would possess a terrifying strength no less than that of his elder brother.

No one would have thought that Konoha’s golden flashes were two men!

- Description from novelbuddy

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates