You should be sorry. The anime came out like 10 years ago. The OVA started 2 years ago.
You'll be waiting a while, the hour-long OVAs come out 1-2 per year. There's 4 out and there's going to be 10.
There's no good reason to watch the anime though. Not a single Nazi character appears, and it doesn't even have Pip. The plot is completely different. Shitsux.