Manga by Masaki Segawa, based on Futaro Yamada's "The Kouga Ninja Scrolls"
Published in the U.S. by Del Rey Manga
Slugline: A dueling-contest title featuring two enemy ninja clans enlisted by the Tokugawa shogun to proxy-fight a war to determine the succession between his son and... another son? A rival's son? Oh, who cares. Wall to wall combat is what we're here for.
They say there are no superheroes in manga. I disagree. Just swap "mutant powers" for "secret ninja techniques" and there you go. Just in the first volume, just of the clearly defined abilities, I see direct parallels to Clayface, Toad, Spiderman and two different applications of Plastic Man/Mr. Fantastic's powers. Two things set manga apart from superheroes, though, novelty and gore. Toad, for example, still has both arms and legs. And Spidey has never taken a scythe blade in the head (AFAIK -- I'm not a big Spidey fan.) You have to go hunting for small-press titles for that kind of thing... or pick up some manga like Basilisk.
The contents of v.1 are as described in the slugline, plus a romance subplot. Since Yamada is better known as the creator of Ninja Scrolls, things are sure to get worse before they get... really, really ugly. And since nobody lets little things like mortal wounds slow them down, there's plenty of potential for multiple, increasingly strange and gruesome duels!
If this is your cup of tea, come and get it!
UPDATED!: Series Update for Basilisk here.