If you've read the synopsis it is pretty self-explanatory. There's a power outage in a prison where there are 5 prisoners and a cat. The plot is quite simple: the characters try to find an exit from the prison.
And there may be a plot twist.
ART: 9/10
The backgrounds are gorgeous. The animation of the characters feels weird in comparison though, but after a while you get used to it and becomes quite charming.
SOUND: 10/10
There aren's many song in the OVA and the most remarkable one is the ending, which is great!
CHARACTER: 10/10
Although you do not get to know the characters completely the little things you get to know about them are enough for the story to make sense. And it is nice to see how their different skills are helpful to the situation they find themselves in.
ENJOYMENT: 10/10
Despite being short it is a very enjoyable story.
OVERALL: 10/10
Personally I didn't know what to expect from the story but I'm amazed with it. Everything was absolutely enjoyable. And it's great how the staff got to tell so many things in just 24 minutes. Definitely one of the best OVAs I've seen.
