Elf Tensei Kara no Cheat Kenkoku-ki - Chapter 6Book 5: -1: The Imperial City

What did death feel like?Ezekiel didn't want to remember. He wished to never experience that void expanse of nothingness ever again.Luckily he had been reincarnated into a world with magic and the sorts. But as a Mechanic!Watch as Ezekiel defies his manaless destiny by walking the path given to him by that Being as a Mechanic born to rule over all.He had been an ordinary person in his last life but he refused to allow that term follow him into the next.“I can still become someone important. Not as an Awakened from Taia, but as a Battle Mechanic from Earth!”

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.

A university student is stuck working on coursework late into the night due to some unfortunate circumstances. After reflecting on the choices she has made so far in her life and looking forward to what she can do once she is finally able to really get her life going, she starts to make her way home.Unfortunately for her, that life is abruptly cut short, and she finds herself in a new world as a new person, one with a fluffy tail at that. She must come to grips with her new reality, no matter how bad it may seem. Luckily, a clumsy kitsune goddess seems to be looking out for her.This little kitsune will go on a journey to improve herself as she learns more about the world she now lives in, struggles through romance, and puts her life together.