Starting as a Class Five Mutant - Chapter 474 -

All Things of this World, Turn to Ashes, Flowing Blade-like Flame!

Crossing over to the world of pirates(the one piece world) , in the era of pirates, the Roja from eleven years ago obtained a Sword Soul system that lets him strengthen infinitely and extract various kinds of skills.

Flowing Blade-like Flame (Ryūjin Jakka) , Mirror Flower, Water Moon (Kyoka Suigetsu), Moon Fang Heaven-Piercer (Getsuga Tensho), Thousand Cherry Blossoms (Senbonzakura)……

“If this sword descend, you may be roasted to death.” Roja looked at Akainu in front of him and seriously said.

- Description from novelupdates

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.

When he was engrossed in the Wizard World, Roger unexpectedly transmigrated to a world that seemed familiar yet strange.In this place, the legendary monsters actually existed, disguising themselves among the populace and becoming a part of this world.Starting from a deserted island, Roger began his career as a Demon Hunter.Although he had an inborn golden touch after transmigrating, what made him somewhat helpless was that it wasn't him with the cheat, but rather just a dilapidated house ready to collapse...After a long time, when Roger ascended to the castle surrounded by mountain peaks,he couldn't help but let out a sincere exclamation:“From a cabin to a castle, the house is too big and hard to manage!”…………This is the story of a Demonic Hunter living in the modern world.

Chu He transmigrated into a barren world as a lowly odd-jobber in the Xia clan. He had initially accepted his fate and was ready to spend his life ordinarily and peacefully. Little did he expect himself to suddenly awaken the Checkpoint System which rewarded him for checking into places!

Ding, congratulations to the Host for successful checking-in. For your first check-in, your reward is the Golden Nine Turns. Ding, congratulations to the Host for successful checking-in. For your twenty-one-thousandth check-in, your reward is the Golden Manifestation of Buddha’s Form.

Chu He was certain that the world outside was too dangerous, so he resolved to not leave the book depository until he became truly invincible and peerless, and thus he stayed for a hundred years. A hundred years later, the Tiger clan attacked the Xia clan and planned to massacre countless humans, it was at that moment that Chu He finally showed his hand!