Dxd Issei : The Gaming Gear - Chapter 3: {}: Issei

Xiao Jinghuai's home has a little thing, soft and adorable, lively and mischievous.Rather than calling her a wife, it would be better to say it's like having another daughter.Some people say: “Young Master Xiao pampers his wife to the point where she only needs to open her mouth to be fed, she's almost become useless!”“Whoever says that, throw them into the sea to feed the sharks!”Another person says: “Young Master Xiao's wife really doesn’t look that great, nowhere near as beautiful as so-and-so!”“Whoever says that, gouge out their eyes to feed the dogs!”Yet another says: “Young Master Xiao spoils his wife excessively, he has become a tyrant of his generation!”“Who says so?”Turning around, just to see the girl's bright and charming little face, “I said it! So what do you want?”He pulled her into his arms, didn't want anything, just wanted her to be his little princess...(Even in this world full of charms, I only have eyes for you.)

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.

The messengers of destruction have once again been sent by their god, bearing the promise of apocalypse.Fire consumes everything, heralding the end of worlds— from Asgard to Atlantis, from heaven to hell. Once again, the fist of the god of destruction is poised to crush the very dimensions of existence, drawing ever closer to its goal. Amidst the chaos, a humble foot soldier—an insignificant speck on the grand stage—struggles to survive, fighting to climb towards the top.This is the combined story of Global Demon King: Starting as the Abyssal Dragon—Stronghold Legends and writer creativity

The pessimistic and negative daughter of a concubine living in the ancient times thought – since life is so difficult, why should one invest serious effort in struggling to live?

The life of an ancient noble woman is often determined and controlled by her family. Moreover, one’s actions often implicate one’s entire family – thus, it is fairly common to see an unexpected calamity result in suffering borne by one’s whole family. Managing to live a good and successful life while retaining one’s dignity is simply too difficult to achieve.

Ah, living in the ancient times is simply too dangerous – we should all just sleep till we die.

- Description from Novelupdates