The game takes place on the world of Auldrant, a planet composed of "Fonons" (known as Fonim (フォニム, Fonimu?) in the Japanese version): a material energy found in all things. Long ago, a new kind of Fonon was discovered, but great chaos was brought with the finding. By using this newest Seventh Fonons, one could read the future. One such Seventh Fonist, Yulia Jue, put in place a future for the world for thousands of years to come. This prophecy of the future's set path became known as the "Score" and is documented on stone tablets which were scattered throughout the world. The nations of Kimlasca-Lanvaldear and Malkuth have fought over the fragments of these tablets for generations, each uncovering them and hoping to discover the future before the other.
As the game commences, the year is ND 2017. Luke fon Fabre, the son of Duke Fabre of the Kimlasca Kingdom, is 17 years old. He is the Light of the Sacred Flame who is destined to bring prosperity to Kimlasca. But since being kidnapped seven years ago by the Malkuth empire, he has been kept confined to the Fabre family mansion. The shock of the kidnapping erased all of Luke's memories prior to the event. But one fateful day, a mysterious woman breaks into the mansion and sets off a chain of events that will change the world forever..."
thank you wikipedia