This series is up to vol 3 & still on going in Japan too. That is why I hate to ask DMP to license any series unless:
1. The series is already completed in Japan.
2. If the series is really, really good that you know it will sell well in both continents. Even this is a crap shoot. For example, I was shocked that Black Sun 1 wasn't selling well really hate the idea that I won't see volume 2 for that one.
But again, you might get lucky. For example, I didn't think June would license the rest of Yamada Yugi's "Close the Last Door" series but after 6 years later - they did!