Toaru Majutsu no Index - Volume 2, Afterword

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.

After crossing over into a world of magic, Dean Bruce was mistaken for a powerful sorcerer. Though he initially intended to sternly refuse the beautiful woman’s request to become her mentor, she offered him far too much to say no!Completely clueless about magic, Dean Bruce had no choice but to make up spells on the spot. However, when he saw the astonishing power unleashed by the beautiful woman after chanting his random incantations, he was stunned.The spells he had carelessly invented… could they really comprehend magic and even forbidden spells?As Dean Bruce ascended to the pinnacle of magical prowess and became the Archmage, he candidly answered a reporter's question during an interview with the Alliance: “ never understood magic. I just made up a few incantations, that's all.”People were in awe of him—this, they believed, was the true humility of a Grand Archmage!

The Red Dragon came from the vast wild wastes, coveting all the strength in the world. It once had countless titles: Mountain's Wrathful Flame, Infernal Calamity, Crimson Emperor, Ashen Dragon......The world trembled under the shadow of the giant dragons. He stirred up the craze of the magic industrial revolution; in the empire he established, Wyverns roared, artillery fired in unison, and steel beasts appeared in the sky and on the land, while disasters from another world rampaged everywhere.“Submit, or die.”Cassius spread his wings, blotting out the sun, and gazed down at the trembling humans, elves, and dwarves below, saying thus.......It is a story about a Red Dragon with a player template conquering, ruling, and transforming an alternate world.(Pseudo of DnD, The Fourth Calamity, Red Dragon)

[Warning: Mature Content 18+, Harem, No NTR!]He was only ten years old when his world turned to ash. Hidden behind a door, shivering with helplessness and fear, the boy peered through the keyhole and watched his parents die. He never knew who killed them. He never even saw the faces of those who took everything from him.The terror was too much for a ten-year old boy. His mind shattered, erasing that night from his memory. And then everything was blank, darkness in front of his eyes as he lost consciousness.When his eyes opened again, a man stood before him, a stranger with a gentle smile and eyes filled with something strange… pity? Or something else?“What happened here boy?”“Happened where?”“You don’t remember, do you?”“Remember what…? Where is father? My Mother?”“I guess this is for the best.”“Good boy. Your father was my dearest friend… and now, you are my responsibility. From now on, you will be my son.”“You have no one left, boy… but I can make sure no one ever takes anything from you again.” The man said gently.And then that man forged him into something inhuman. A weapon honed to perfection, a shadow lurking in the underworld. The mere whisper of his name - Draugr, A ghost that never truly dies, sent grown men into cold sweats, their legs trembling beneath them.The boy soon outgrew his master and carved his own legend in blood. But all this while he never stopped searching—for the ones who killed his parents, for the truth, for revenge.And finally, after fifteen years of silence, he was close. The last clue he needed was just within his grasp.It was so close, yet just an inch out of his grasp. He was ambushed, a trap he never saw coming.Wounded, bleeding out, fighting for his life against an army of men and women eyeing to claim his life, he should have died. But fate had something else stored for him.Barely holding onto life, he stumbled into a girl—fragile-looking, yet completely unafraid of the monster before her. She didn’t run. She didn’t scream. Instead, she smiled.She saved him. Took him to a hospital. And as he lay unconscious, she made her plans.But when he woke up… He had lost everything, He remembered nothing.Not just the truth of his parents' murder. Not just the years of searching. Not just the enemies and allies he'd made along the way. Not even his own name.Twenty-five years of his life—wiped clean.Now, in a world that fears his very name, with ghosts of a past he can no longer remember hunting him in the shadows—he must decide: Is he still the Draugr they all fear? Or is he just a man searching for the pieces of himself?And who is the girl who stole his fate and bound it to hers?