The year 743.
Mankind was facing the danger of extinction at the hands of the Titans that had suddenly appeared at the center stage of history. Where had they come from, and what was their purpose? Some said that they were natural disasters, while others insisted that they were divine retribution. Either way, mankind had been reduced to simple, clueless prey whose total population had plummeted to 500,000.
Humanity had moved to living inside the walled cities because there was no other way to resist the Titans. In other words, humanity avoided the worst of all outcomes, extinction, by deciding to become a species of caged birds. Mankind had been given 720,000 square kilometers to live in. While the soil was hardly fertile, there was at least enough space to live a modest existence. Encircling the area was the key wall of the walled cities─Wall Maria. The firm wall stood fifty meters tall and stretched for a total of 3,200 kilometers, perfectly isolating the interior from invading Titans.
Wall Maria was not the only wall. Waiting a hundred kilometers farther in was a second wall, Wall Rose, and past that was Wall Sheena, the last line of defense. These three protective walls allowed humanity to regain peace, though it was a temporary one.
Even now, a little over thirty years after the Titans appeared, Titans and humans still stood as predators and prey. The Titans’ behavior remained full of mysteries. Little was known about them other than the fact that they preyed on humans. The worst part of it all was that they did not know the Titans’ weakness. Humanity had yet to win a battle against the Titans, and it was now common knowledge that the Titans were immortal. Only having gleaned that much in more than a quarter-century was quite shabby, but it was no surprise as people had not been aggressive in surveying or investigating the Titans.
No need to take back the outside world.
Live happily while you can.
An unwritten code, that mankind was fated to live as caged birds, had spread among the people.