The Guardian gods - Chapter 245

After dying in the world of One Piece, he was reincarnated once again this time as Neji Hyuga. But fate was no kinder here. With his father dead and the cursed Caged Bird Seal looming over him, for his survival he made a ruthless decision....

Nicholas Marjan—known as Niels—was once an Asian football-obsessed loner in the modern world. A master of FIFA Career Mode, addicted to tactical YouTube breakdowns, and endlessly chasing transfer window drama, he lived the beautiful game from behind a screen.Until the day he died.Reborn in the late 2000s in a small European country, Niels wakes up in the body of a once-promising young footballer whose career was tragically cut short by a brutal ACL injury. With no chance to play again, and haunted by the weight of lost potential, the only path forward is through coaching.Now an assistant at a struggling lower-league club, Niels carries two things no one else has:-Knowledge of football’s future-A mysterious cheat-like instinct for scouting raw, hidden talentAs he begins to make waves with his unique coaching style, Niels catches the attention of the football world. Offers from top-tier teams in the top five European leagues come rolling in. With a growing reputation, Niels sets out to transform not just one team's fate—but to leave his mark on the biggest stages in world football.

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.

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.