I'm Leveling Up Too Quickly - Chapter 4 - I Really Want to Be an Ordinary Person

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.

Yukima Azuma—charismatic, confident, and utterly unforgettable. He was the man every girl wanted but could never truly keep. One by one, they fell for him, only to be left with memories they couldn’t erase.Kasumigaoka Utaha: “I was his first, the one who taught him love… only for him to use it on other women.”Sawamura Eriri: “If I hadn’t been such a tsundere, maybe things would have been different.”Yukinoshita Yukino: “He was my light in the darkness, the only one who ever truly saw me.”Yukinoshita Haruno: “That bastard ran away after taking everything from me.”Hoshino Ai: “My only true love. The one I can never replace.”And when asked about their relationship with him?“Ex-girlfriend.”But to the women still in his life?Sora Ginko, Kato Megumi, Sagiri, Bocchi, Shinomiya Kaguya, Kirisu Mafuyu, Suou Yuki, Alya—“Thieving cats.”Because no matter how much time passed, no matter how far he went—one truth remained: Yukima Azuma was the one man they could never forget.

After transmigrating to Hong Huang and becoming a minor shaman in Hou Tu’s tribe, Chu Xuan shocked everyone by repeatedly offering poisonous plans in order to avoid becoming Cannon Fodder in the Great Calamity.Who would have thought? The poisonous plans were incredibly effective.The Demon Clan established the Heavenly Court and united countless races?Chu Xuan: Establish the path of the Heavenly Tribulation and share the power with the Heavenly Court. From now on, all beings must undergo the tribulation!In Zixiao Palace, it was said that those without Primordial Spirits couldn’t listen to the Dao?Chu Xuan: Create the path of the Heavenly Demon as a tribulation for Primordial Spirits. All who possess one will suffer!During the war between the Wu race and Demons, countless souls were left with no place to go, and the Calamity Qi of heaven and earth ran rampant. Who asked Hou Tu to reincarnate?Chu Xuan: If you don’t work hard in your cultivation, you’ll end up as brothers in the Ten Thousand Souls Banner.…Chu Xuan: I have a plan that can completely resolve the Great Calamity of the Demons and Wu races!Hou Tu: Chu Xuan, calm down first. Things haven’t come to that point yet.

Okay, so let me get this straight. I wake up and BAM, I'm inside the body of Valerian Thorne—a third-rate villain. I mean, come on? Out of all the characters I might have been reincarnated as, it had to be him? This man was literally a stepping stone for the actual hero. So why him? Why not someone with a little more. potential?Now that I have a system that can unleash Valerian's hidden potential, who knows? Perhaps this third-rate villain will get a second chance, alter his destiny, and prove the world what he is truly capable of. And if I happen to get to keep the gorgeous fiancée in the process. well, I'm not complaining.