Was this supposed to be longer? There seems to be a lot of back story, but it barely touched on it. We get a glimpse of it, but that isn't enough. This OVA was only three episodes long, and it should of had added another episode, so we could at least get to know the characters, and sympathize with them. Instead, I felt like I didn't really care what happened to them. We also see a few characters who pop up a few times, which just seems out of place. I think we were meant to have seen more of them.
It wasn't bad though. It did a pretty good job on the action side, but they could have explained more about it. It seemed like the creator was inspired after watching Karas. That's what I though of first when I started watching it. It was entertaining, so I guess it did its job. It just needed to be longer. Probably then, this could have been an amazing OVA.