Before "The Great Smog", there was much war between America and Japan. The president of The United States ordered the termination of Japan by creating a gas that was filled with glass and chemicals that covered all of Japan in one day. This wiped out 90% of the country. The ocean, crops, animals, and humans were all turned into ashes. "Turned back into the dust of the ground", as some would say. It's been 80 years since and now America owns Japan just like they had planned.
In 2080, 60 years after "The Great Smog", Aliens asked for Earth's help in finding a world that they could inhabit. America was the first country to get in contact with the Aliens. During the search for another planet, The United States decided to give the Aliens Japan, though it was still uninhabitable to humans for at least another 40 years.
Now it's the year 2100. A USB was sent to a girl named Anna Jackson in Seoul, South Korea. The USB had information explaining how she would help end the war and prevent "The Great Smog" from ever occurring. How was that even possible? Well, perhaps with a time machine.