Final Fantasy XIII-2 was announced last week, and it hasn't taken long for the first pieces of information to be revealed about the game's story.
According to a translated interview with Dengeki Magazine in Japan, the game will focus around the Goddess Etro, and Lightning's search for the key to an invisible world called Bunibelle.
They also disclosed that many of the game's older characters will return in this sequel, but they might not be as you remember them. The game will also have a much darker tone.
Source: Final Fantasy Union