Toaru Majutsu no Index: Genesis Testament - Volume 3, Chapter 4: The Demon Lord’s Young — the_LIGHT.

Will, a seasoned game designer, found himself reincarnated as the disposable villain in a cliché “kicked out of the party” novel. Faced with his inevitable tragic fate, he had one ambitious dream: to turn the pitiful “losers” from the protagonist’s harem into terrifying blackened bosses who would torment the protagonist!He taught the timid and cowardly wolf-girl maid to imprison the one she loves forever by her side.He trained the tsundere, sharp-tongued loli witch to make her beloved see only her in his eyes.He guided the cold and clueless half-elf princess to use…—

There are 2 paths to achieve the peak of power, the Tenth Stage.Gain the recognition of Laws and ascend as a God.Or Cultivate thyself as an Immortal.With his Master unparalleled in Energy Manipulation and Space-Time, watch as Fang Lin achieve both!!!Burdened with a master that can shake cities and crush mountains, Fang Lin travels the realm, cleaning up after his master's messes!!!Discord Link: https://discord.gg/uS8FvQG

The new book is out! Meng Yunhan has been reincarnated back to the time of ‘food coupon era’, a time when people struggled with food and clothe shortages. But she is not afraid this time around. Equipped with a ‘cheat code’, she is ready not only to start her own business but also to grab a hold of her stoned-face brother and even support Baozi, her child.Stoned-face brother: “Wife, let’s pack up Baozi and leave!” He claims that having a son who is even clingier to his wife than himself is utterly shameless!“Mommy, let’s get a new daddy!” Baozi suggests. His daddy, a grown man, is still so clingy to mommy. How disgraceful!

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.