Ace of the Dragon Division - Chapter 12 - Blocked

The empire has turned into the land of the undead due to a spell gone wrong. God summoned heroes from countless worlds to purify the empire and plant new hope. Lee Shin Woo, an ordinary earthling, was also summoned. As an undead, that is.

Holographic viewing technology allowed audience members to enter a movie and personally experience it for themselves. Naturally, romance movies were the most popular and well-received, while nobody was interested in horror movies.

Su Min was the first of the viewers to experience a horror movie.

Later–

Malicious Spirit: I dare not scare or frighten my sweetheart…

Su Min: Actually, horror movies aren’t scary at all.

Audience: No, no, no, you are playing in a love movie! (Loudly)

The audience suddenly discovered that the recent rerelease of the horror movie was much better than the original. Furthermore, to everyone’s surprise, the ghost was very sweet…

- Description from Novelupdates

This story revolves around a boy who was sent to a dark, mysterious parallel world in the body of his beautiful senior sister known as Lily. The lone girl ran into the night parade of a hundred ghosts the very day she arrived; seeking survival amongst the warrior’s dispute in a chaotic world, and forging her own demon sword! This is an unimaginable other world adventure!

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.