This entry talks about the tragedy that occurred at the concert in episode 1, it details a lot information that was never mentioned in the anime. This is a pretty depressing read, since it goes over the number of people in attendance and how many died.
For those of you that didn't know, the Symphogear concert had exclusive goods available for purchase. Due to large lines (of over 700 people!) at the concert, they announced afterwards that all the items would be available for order on Good Smile's online shop. Much to my surprise, these goods have also been made available on the international shop as well so that overseas fans can buy them!