D.E.M.O.N.S: Getting Summoned Weekly isn't so Bad - Chapter 1550 - Stay Or Go

Thirty thousand years ago, the Heaven Fighting Race who called themselves “Gods” invaded the Spirit Realm. Hundreds of races rose up in resistance, but ultimately suffered a crushing defeat. The Human Race was the first to concede, and the rest of the Hundred Races soon followed in succession.

A teenager who unexpectedly gets transported to the modern world from ‘the world of the immortals’ . He finds himself in the body of an ordinary guy. He wants to go back to his world and for that, he will have to practice to get stronger and investigate the reason why and how he crossed through to this world.

Lin Jiufeng transmigrates to become the Yuhua God Dynasty’s Crown Prince but is dethroned, banished to the Cold Palace, and imprisoned there because he had released the holy maiden of their rival country.Lin Jiufeng isn’t dejected. He has brought a sign-in system with him when he transmigrated and he would receive rewards when he signs in at different places.Before the Cold Palace’s gates, he signs in and receives the Ultimate Heaven Slashing Sword Skill!In the Great Council Hall, he signs in and receives the Heaven Patching Technique!In the Empress Dowager’s palace, he signs in and receives the God of War Totem!…Liu Jiufeng imagines that he can quietly sign in like this until he becomes invincible. Yet who would have imagined that the Heavenly Concubine whom he secretly released would rise in rebellion and seize power after she returns to her country?After she succeeds, her first priority is to attack the Yuhua God Dynasty to rescue Lin Jiufeng.When Liu Jiufeng hears of this news, he’s puzzled. “Do I need you to rescue me?”

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.