Square Enix has confimed that Kazushige Nojima, the writer of many of Final Fantasy's greatest stories, will not be directly involved with Final Fantasy XIII-2, despite being the person who came up with the concept for Final Fantasy XIII.
Speaking to us at this year's E3, Motomu Toriyama, the game's director, said: "Nojima is still indirectly involved because he's a writer for Fabula Nova Crystallis which is the mythology that all the Final Fantasy XIII games are based on. In that way he's contributing, but not directly."
Square Enix has opted to hire a professional novelist instead called Jun Eishima. He wrote Final Fantasy XIII Episode -i-, which released with the Japanese Xbox 360 version of Final Fantasy XIII, and he will write the main scenario for Final Fantasy XIII-2.
"It's going to be a different system this time around," said Toriyama. "After Final Fantasy XIII was released there was a side story (Episode i) released and a professional novelist called mister (Jun) Eishima contributed to the side story, he actually wrote the scenario basically."
UPDATE: From the comments, I felt it was necessary to update things slightly.
Firstly, the translator referred to Jun Eishima as MISTER Eishima and thereafter referred to Jun Eishima as "he" not "she". Therefore it's not us that got it wrong, it was them. We were just using the information given to us.
Secondly, we spoke directly with Toriyama. Therefore, there is no source. We have the audio recording to back up what was said if Square Enix want to dispute it with us - they haven't contacted us so far.