I became a legion lich - Chapter 258 - Adapted strategies

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 girl who calls herself a demon appeared before a timid student named Fumio Kijima. The girl claims to be a campaign girl from the demon world and she gives him the ability to “summon a room” from nothing but thin air.

At first he doesn’t abuse his power and uses it as a convenient ability in his every day life. But one day he is bullied by his classmates under a false pretext and is made to suffer. In the past he would have wallowed in misery and cried himself to sleep, but now he had a power to call upon.

“I will make them regret it!”

Using his powers to summon his “room”, he begins his era of confinement and brainwashing to achieve his goals.

“Let go of that kitty cat!”

Bai Feng transmigrated into the game and became a formidable giant of the demon race, Bai Qingling.In the game, Bai Qingling was a scheming and cold-hearted character who would do anything for immortality. He practiced the art of Voodoo, created human puppets, and committed all sorts of evil deeds.What's even more despicable was that he always treated his three adopted stunning female disciples as pawns, making them the common antagonistic bosses in the “pure love” and “fallen evil” paths of the game!Bai Feng's arrival happened to coincide with the game's finale. At this moment, Bai Qingling was severely injured, completely depleted of mana, and about to be betrayed by those around him!In order to protect himself, Bai Feng had no choice but to intensify his wickedness and interact with those around him with the most ruthless and evil demeanor.But little did he expect that...Eldest Disciple: What a great immortal Master is! I really want to cry!Second Disciple: People misunderstand him so much. Master is truly a great immortal of love!Third Disciple: If we can contribute to Master's quest for immortality by sacrificing everything, what are we waiting for?Righteous Fairy: Master, if you don't abandon me, I will be willing to abandon the light and embrace the darkness, serving you faithfully!