---News --- September 9th, 2009
Quick news... During the Final Fantasy XIII premiere party, Square Enix showed off a 'sample' of the theme song for the game. This may just be the featured song of the game that usually has the singing in the background, as opposed to the main instrumental, reoccurring theme during the world map and game-play through-out the game.

The song is titled “Kimi ga Iru Kara,” and the track is and will be performed by Sayuri Sugiwara, who is also singing at least another song in the game.

Anyways, be sure to check it here:
A taste of Final Fantasy XIII?s theme song

Source: Examiner