I don't even know if you need anything else in that universe though. Not like Hollywood wouldn't make some stupid ass deal using the setting. I mean do you really trust them to handle the IP?
Was a good story and what the hell else are you going to add to it. I'm at the comic or Manga has a lot more material, I think I have a couple of issues from the American prints and it planned on buying them all when I was a teenager, but I couldn't find the whole set.
I'm sure there's probably an omnibus out there, and I wouldn't mind getting it at some point. Hell you could probably download the damn thing, but I guess I'd rather have it in my hands.