Reverse World - Chapter 121 - – Announcement

In the Sky Sword Continent there are thousands of sects and strong cultivators as common as trees. In order to prevent his older sister from being forcefully married off, Lu Xuan had no choice to but to unceasingly cultivate and enter a sect to ask for a favor. By chance, a sword-shaped crystal of mysterious origins entered into Lu Xuan’s body, containing countless top-class martial skills, powerful martial arts, and everything you could wish for! A martial legend starts here…

- Description from Novelupdates

Crossing to One Piece world, he became Roger’s younger brother.

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- 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.

“I am Bianca Valestra, Witch of the Frozen Night, an enemy of Humanity. By choosing to follow me, you will be fighting not just humans—but the entire world. I no longer wish to lie to you, Elian. If you wish to walk away or choose another path, I will let you.”Yet the boy shook his head and laid his hand gently over hers.“I am no longer human. I just committed what I think to be genocide. I am not afraid. For you—the one who saved me, gave me purpose, and my only desire—I will fight. I do not care how many come. I will kill them all.”___In the year 2030, everything changed.Portals to other dimensions appeared without warning.We called them dungeons.And from them came monsters that knew only destruction.But in humanity’s darkest hour, a sliver of hope emerged.People began awakening strange abilities—Talents—to fight back.Years passed. A fragile normal returned.Our story begins with Elian Reeds, a teenage student born in this new world—without a Talent.A Defect, they called him. Useless. Broken.That is, until he meets her.A fallen villainess whose name still strikes fear and reverence alike:Bianca Valestra—divine in beauty, and colder than death.This is the tale of their meeting.The chronicle of their journey.And the legacy of their triumph.