Blacksmith of the Apocalypse - 1430. Through the Cave

At the Tristain Magic Academy, her classmates call bumbling witch-in-training Louise Francoise le Blanc de la Valliere “Louise the Zero.” During an important coming-of-age ritual, when each student must summon their own witch’s familiar, Louise confirms her classmates’ opinion by accidentally conjuring up a normal teenage boy from Japan. Whether the two of them like it or not, the laws of magic bind them as master and servant forever! A hilarious novel with romance interwined.

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.

Wang Chen, a sore loser, was on his way back to his apartment after being rejected by his company boss once again. As he approached the alleyway leading to his apartment, he was suddenly knocked out by the most beautiful woman he had ever seen from the blue star planet.The woman kissed him and then threw him into a void that led to another world. When Wang Chen woke up, he realized that he had been transmigrated into the body of another nobody loser in this new world. He thought that his new life would be even more tragic than his previous one, but suddenly something strange happened.[Ding! Found a suitable successor for Destiny Transfer System][Does the successor want to bind with the system?]How could Wang Chen miss this opportunity to turn his life around? He quickly responded with a “yes.”[Congratulations, host, for binding with the Destiny Transfer System.][With the help of the system, you can loot other people's chances. If you manage to loot the chances of the protagonist, conquer the heroines, and steal their luck, you will receive additional benefits.]“Hahaha,” Wang Chen laughed, thinking that his life would be amazing from now on.However, little did Wang Chen know that he was now a crucial piece in a mysterious conspiracy involving powerful immortal beings who controlled the cosmos.Would Wang Chen be able to survive in this new world and uncover the truth behind the conspiracy, or would he become a pawn in a much larger game?