Final Fantasy XIII is set in the world of Cocoon, a floating colony filled with millions of human lives that have closed themselves off from the world below. Cocoon is also watched over by a giant mechanical race of beings known as the Fal'Cie, who are responsible for things such as regulating weather to all the food production for the population. In essence, they are the caretakers for the human inhabitants. But all is not well in Cocoon. A conflict between the military and a group of civilians has broken out, and as the battle wages on for the first bit of the game you are introduced to all the main characters of the story. You play with different people at different points for this part of the game, being introduced to them and their role in the overall situation. Eventually, the entire cast is assembled inside of a Fal'Cie seemingly by chance.