According to Japan Expo's homepage, Pata's band Ra:IN will perform on 6th July 2008 at 17:00 at the "J.E. Livehouse", a concert hall inside of the JE venue.
The concert will be 45 minutes long and a autograph session will take place after that at 18.00!
Personal comment: YAY!
Edit: the autograph session will take 45 minutes and will be for only 45 people. I think it'll be a lottery drawing again..