Mystery Descends: My Exchanges Are Not Equal - Chapter 51: Another Upgrade! Secret Assassination! (Please bookmark! Please vote!)

I possessed a minor character who marries the prince. I’m not thrilled about it. The prince is a scumbag who flirts with the heroine despite being engaged and eventually gets defeated by the original male lead. In the epilogue, all he does is apologize to his fiancée and marry her, with barely a line to his name. Well, his personality is twisted, but at least he’s handsome. And since he’s the third prince, he doesn’t have to shoulder the burden of ruling the kingdom. That’s decent husband material, I suppose. Go ahead, make a fool of yourself. You’re going to marry me anyway. I’ll just sit back and enjoy watching your embarrassing history unfold. “Doris Redfield. Don’t expect me to ask you to dance at this ball. Maybe not at the next one either. Or the one after that.” “Yes, Your Highness. As you wish.” “Even though we’re engaged… wait, what?” “It’s just a joke proposal our parents once tossed around, isn’t it? You don’t need to take it seriously, Your Highness. I’m really fine with it.” “…Is that so? Yes, that’s… fine, right?” Why are you panicking, prince? You started spouting nonsense first. Where’s your conscience? But then, this guy really has the audacity to ask something outrageous. “…Do you, perhaps, have another man?” The guy who flirted with the original heroine is saying this now? Calm down. He’ll regret this later. All I need to do is remain a devoted fiancée until then. “What are you talking about? A woman like me… plain, not beautiful, with a gloomy personality, what man would even—” “What? Who dared to say that about you?” …You did, in the original story. This guy is acting weird. But he’s not the only problem. “My dear little sister Doris, that dress you’re wearing today is dreadful. No wonder there are rumors His Highness has abandoned you.” “Well, it can’t be helped. His Highness is too good for me anyway.” “…Hold on. Too good? Who said that? Wait, were you really dumped?” The original villainess, who also happens to be my older sister, Natalie, is suddenly interested in my love life. Why are all the original tr*shy characters growling at each other over me now?!

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 Emperor had issued an official decree to appoint a successor to the throne—one who would become the next ruler of the empire.But instead of a direct appointment, the successor would be determined through a formal battle among the princes and princesses.A battle that would drag in many factions, overflow with conspiracies, claim countless lives, and reshape the entire continent... was about to begin.But among the contenders, there was one prince who had no intention of fighting—Nolan.Handsome, lazy, and utterly annoying, Nolan was well-known for the many unflattering titles given to him by those around him.Nolan: “Fighting to become emperor? Please... I just want to relax and enjoy life.”Rather than compete, he convinced his twin sister to fight in his place while he supported her from behind the scenes.Nolan: “My dear sister, I leave my future in your capable hands!”And with that, the prince’s journey toward a life of leisure—relying entirely on his sister—officially began.

The head of the London Association of Mages, the most powerful Saint Archmage in the world, Audrey Davis, accidentally transmigrated to another world due to a magic accident. She was an 18-year-old human girl.