A Guide to Raising Your Natural Enemy - Chapter 52

It tells a poignant love story. He was the most heroic man in history, and before his death he sang a sad song about a woman; she was the most charming woman in history, and before her death she danced a story about steadfast love. The story of the two had no beginning, only an ending of parting in death. After his death, he became a demon for her, and fought fiercely with the immortals of the three realms. After he was killed, his unique seven souls were hidden in various places by the immortals; she became a ghost for him, and before she passed away, she smashed Meng Po's soup bowl, and her soul flew away. Even so, he still vowed to subvert the three realms, find her in the next reincarnation, and marry her, even if it took a thousand years.

Traveling through the world of One Piece, Ron, who became Kuina’s fiancé, awakened the god-level theft system.

In order to become stronger and change the fate of Kuina’s death, and to survive in this dangerous era of great pirates, Ron started to steal Sauron’s top kendo talent.

And that’s just the beginning.

In order to become stronger, Ron embarked on a journey to steal the talents of the world’s strongest.

“Ding! Congratulations to the host for stealing Karp’s physical talent!”

“Ding! Congratulations to the host for stealing Nika’s talent!”

“Ding! Congratulations to the host for stealing Shanks’ domineering talent!”

“Ding! Congratulations to the host…”

- Description from novelbuddy

“For a long time, we humans have been like the chosen race, without any natural enemies, and have long been at the top of the food chain. Unfortunately, I have to tell you...” “When there is only one bird in a forest, then the forest is basically fake, and the bird was put there by someone...” “No matter how a fish swims, it can never meet any of its kind, which only means that the fish is kept in a fish tank...” “Yes, we are the birds in the forest and the fish in the tank.” “Yes, the world we live in is virtual!”

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.