Douluo Dalu: The Legend of Heavenly Ruler - Chapter 308: Crimson Dawn

Seong Eugene, a student at Gukcheon University, is recognized for his latent potential as a hunter but shows no signs of awakening by the age of 21.One day, his intense desire to awaken triggers his latent abilities, and he awakens with a new smartphone app.He invests five points to increase his physical attributes, specifically enlarging his penis to 16 cm. As he explores his abilities, he discovers he can conduct random draws for items and skills, acquiring several items and a complete recovery skill. His unique ability allows him to enter fictional worlds, and he decides to test this by entering an AV film he watched a week earlier, SV-7495.

She was dressed in white, with a mysterious orchid imprint on her forehead, her skin like jade is always covered with a veil. Since childhood, she had left her parents due to her special status and lived her life with her master in the clouds. She was not yet ten when her medicinal skills were renowned in the world. In order to save the people, she descended the mountains, however, she encountered a storm on the way to the epidemic area. The man who saved her would tease her for enjoyment, little did they know…

A mortal teenager strayed into the immortal way because of an accident, struggling on the road of seeking immortality.

Immortal Road is difficult to climb to the sky, in the face of numerous obstacles, his desire to seek the truth is still unabated.

Looking back again, the green mountains are still there, so the old is boneless.

- Description from novelbuddy

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.