Pet Simulator - Chapter 307

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

Tachikawa Shin always thought he was a decent, upright man—unfortunately, he’d been saddled with an indecent favorability system.Raise others’ affection to grow stronger?“I’d rather stay away from these witches, but this concerns my safety and physical integrity... Well, it seems I don’t have a choice,” Tachikawa Shin said righteously, with absolutely no perversion whatsoever.All hail the Rizzler!

Athena Grant,a human,dies in a car accident and becomes Eira Liora,an elf. Transported to the barren and cursed island of Luinmir, a once-thriving land now abandoned.A year ago,their King announced that the island,Luinmir would no longer be under the empire's control. It was well known that the land was barren and poverty stricken...She was abandoned both by her Kingdom and her Father.She wakes up one day with a system.“So what if they were abandoned and deemed cursed,she would show them all the highest peak of knowledge and development. The island's core is broken...fine,she'll get it replaced but this time,the island would become hers to keep,she would make sure of that.”

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.