Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 84 - : Calculation

Seventeen-year-old Hajime Nagumo is your average, everyday otaku. However, his simple life of pulling all-nighters and sleeping in school is suddenly turned upside down when he, along with the rest of his class, is summoned to a fantasy world!

They’re treated like heroes and tasked with the duty of saving the human race from utter extinction.

But what should have been any otaku’s wet dream quickly turns into Hajime’s nightmare? While the rest of his class are blessed with godlike powers, Hajime’s job, Synergist, only has a single transmutation skill. Ridiculed and bullied by his classmates for being weak, he soon finds himself in despair.

Will he be able to survive in this dangerous world of monsters and demons with only a glorified blacksmith’s level of strength?

Life is unpredictable. Her husband loved her stepsister, deposed her as Empress and even forced her son to death. In that Cold Palace, she was forced to drink poisonous wine. So in the next lifetime, she made a promise to never do good deeds and help others, to never step into the palace and to never become the Empress!

Six years ago, the legitimate daughter of the Chu Family was schemed against by her half-sister and was forced to marry the Princely Heir, who was blind and not long for this world.Fortunately, her medical skills were excellent, and she detoxified the Princely Heir.Who would have thought after he came back to life, the emperor would actually want to bestow a concubine upon him—and this jerk didn't even refuse.Furious, she left a divorce letter and then set the Prince Residence on fire, fleeing in haste.Six years later, the same Princely Heir remained a lonely man, with all his old servants worrying their hearts out.One day, upon encountering a Little Baozi on the street who looked strikingly like the Princely Heir, they instantly burst into tears.“The Prince Residence has a successor! Princely Heir, please come back with us to the Prince Residence quickly.”Who knew, Little Baozi disdainfully said, “Not interested.”“Princely Heir, the Prince Residence is immensely wealthy...”“My mother is the wealthiest person!”“Princely Heir, the Prince Residence is extremely safe...”“My mother is the Martial Arts Alliance Hierarch!”“Princely Heir, the Prince Residence has powerful armies...”“My mother is the heir to the Nanduan Kingdom!”Suddenly, a faint voice came from behind: “Then, does your mother need an Imperial Consort? I think myself quite suitable.”

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.