More information was revealed by Akiba Hobby in their report of Black Rock Shooter Event which was held yesterday .
They have more pics there, feel free to follow the link. As to the long text, there is something about BRS promotional campaign which will run this summer and will include a kind of 50-minute length anime streamed for free.
Also some of the cast was announced:
- Kana Hanazawa as Mato Kuroi (BRS)
- Miyuki Sawashiro as Yomi Takanashi (Deadmaster)