MTL - Very Happy - ~ big boss

[Simulation] + [Isekai] + [Goblin] + [Harem]After a long sleep, I awakened in a new life—as a goblin. Weak and insignificant, I found myself reborn as the lowest creature in a world filled with hostility and danger. But from the shadows of this cruel world, a silent rise begins...

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.

Luck wasn't on his side as when he was just few steps away from becoming the world champion in karate he was killed by his by his opponents scheme who was afraid to fight against him and wanted the cup. But he was once again given a chance to reborn as Kenichi Shirahama and become the strongest martial artist.Watch and see how he conquers the world by becoming the strongest disciple and also how he conquers the women's he likes in his HaremI have reuploaded the chapters again as to the problem of Power stones that occurred in the previous one.

Tae-seo, a villain who tormented the main character in an Omega verse novel, suddenly finds himself reincarnated into that very antagonist role. What’s worse, he reincarnates just as he’s about to administer a heat-inducing drug to the main character!Tae-seo, the protagonist of the original story, thwarts Seo Da-rae’s plan to administer the drug and, in order to avoid triggering a dead flag, casually drinks the inducer. Reincarnated not as an Omega but as a Beta, Tae-seo expects nothing out of the ordinary to happen.“Well, causing a cycle right here is quite audacious. Or are you asking just anyone to pick you up?”Unfortunately, due to side effects, Tae-seo manifests as an Omega and experiences the heat cycle. By chance, he ends up sharing a bed with a man named Kang Se-heon.“Don’t expect me to take responsibility later. I have no intention of being manipulated by a bloodthirsty person like you.”“I don’t have any intention of asking you to take responsibility either.”Initially unaware of his relatively minor role in the original story, Tae-seo is surprised to learn that Kang Se-heon happens to be the main character’s cousin. As Se-heon starts approaching Tae-seo in a suspicious manner and even other characters from the original story oddly gravitate towards him, Tae-seo’s confusion deepens.“Yoon Tae-seo, you should choose me, even if it’s for the sake of the child.”Will Tae-seo be able to navigate through the night with Kang Se-heon and escape the grasp of the original story’s main characters unscathed?