Brothel Manager : Unexpected Encounter with A Hidden Family Heirloom - Chapter 28 - : change of Plans

Karl Adelheit, a self-proclaimed ordinary student returning from military service.

And a nobleman who enlisted as a soldier and received Medals of Honor.

Kain can control luck because of the curse, doomed to run from death - forever.“I lost everything again...?” Kain muttered. The Keepers fell as the monsters burst out of the Rift.Unlike the others, he hated Keepers, the only people capable of fighting the creatures from the Astral Dimension. Everyone saw them as heroes, but Kain blamed them for the greatest tragedy of his life - the death of his parents.Ironically, the sacrifice of one Keeper allowed Kain to obtain a Rune Brand - the key to begin a trial, the outcome was either power or death.Facing another world, Kain discovered that his blood was cursed, and misfortune would always haunt him.But death would avoid Kain, wanting to keep such a valuable sacrifice for a god. Only failure would await him, but if it were possible, death would pass by.Now, Kain must break his curse and take fate into his own hands for the first time in his life or remain a nameless offering.

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.

Kōdo Ikusei Senior High School, a leading prestigious school with state-of-the-art facilities where nearly 100% of students go on to university or find employment. The students there have the freedom to wear any hairstyle and bring any personal effects they desire. Kōdo Ikusei is a paradise-like school, but the truth is that only the most superior of students receive favorable treatment.

The protagonist Kiyotaka Ayanokōji is a student of D-class, which is where the school dumps its “inferior” students in order to ridicule them. For a certain reason, Kiyotaka was careless on his entrance examination, and was put in D-class. After meeting Suzune Horikita and Kikyō Kushida, two other students in his class, Kiyotaka’s situation begins to change.