This legendary manga series has been getting its first English releases on a monthly basis since November. 10 have been released thus far, and another 4 have been announced (see here).
Volume 1 is technically coming up in the system, but it is currently being listed as coming from Nobrow press, but that is a different book named Kingdom from author Jon McNaught. The manga is being published by Viz Media (and likely will for some time since there have been 80 volumes already printed in Japan!). Probably a good time to get it sorted here.