Norageki!

Norageki! (ノラゲキ！, lit. Five Numbers!) is an OVA made by Sunrise. Only one episode has been released.

Plot
The story is set in a certain isolated prison with four prisoners and a cat. One day, a sudden power outage opens the locks and everyone is mysteriously set free from their cells. However, all of the guards are missing, and the prisoners cannot find any exits.