As I understand it, they were GOING to do a sequel, but the project was closed ... (it was said in the OVE that there would be a sequel). Maybe it will be like with Durarara (5 years break, and then the continuation), well, at least I hope :D
Neither the zombie plot nor any other plot was promoted by this OVA. So the end is still too open for me. But at least some kisses were delivered here. This was not enough in the series itself.
I do not know why I like it.
Oh, I think I do..