Kiyo QJO series was previously released in North America by Tokyopop
Viz's Select label has begun selling Zone-00 on digital formats including their own platform, Kindle, Nook, iBookStore and GooglePlay. The 2000 manga by Kiyo QJO was previously released in North America by Tokyopop.
They describe the series:
In a world where humans and demons coexist under a fragile peace, change is coming...A mysterious drug, known only as "Zone-00," seems to be causing demons all over Tokyo to lose control and revert to their old, violent ways. Enter two young students who stand on opposite sides of an ageless conflict. One a demon, the other an exorcist, they must now join forces to uncover the secret of "Zone-00" before it's too late! From the artist of Trinity Blood comes a dark, suspensful tale in which two centuries-old enemies fight together to save humanity!