Kiss Me if You Can - Chapter 26Vol 1.

While on a school field trip in the Czech Republic, Kang Hyuk happens to stumble into a shop called “Archmage.” To his disbelief, the shop is actually owned by an archmage… from another world! Forced to become the Archmage’s disciple, Kang Hyuk is punted into the Kallian Continent, where might and magic overwhelm and wyverns fly high in the sky…

In this world, people are either sword-wielding knights, magic-wielding mages, or spirit-wielding summoners. There hasn’t been anyone yet who can do all three… until now.

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.

Pain, Pain, Go Away is a novel by Sugaru Miaki, also known as Fafoo, author of Starting Over and Three Days of Happiness. Unlike Miaki’s previous two books, Pain, Pain, Go Away is not a rewrite of any story posted to 2ch, but an entirely original one.

The plot involves a young man who becomes a killer (by accident) – but his victim has the power of “postponement,” temporarily delaying her death.

The Nightmare BeginsDr. Emma Taylor, a renowned psychologist, had always been fascinated by the human mind's darkest corners. Her latest patient, a young woman named Sarah, suffered from terrifying nightmares that seemed all too real.