Anime fans ought to be at least passingly familiar with Hakkenden, the 13-episode adaptation of Bakin Takizawa's feudal-era epic about eight reincarnated warriors embodying different samurai ideals. Readers of this site probably remember the Sonny Chiba live-action version, directed by Kinji Fukasaku, which doesn't hew quite as closely to the original story but is rollicking as all get-out. I've been planning to do a rundown of the series since its LaserDisc days — yes, that long ago — but with the current Geneon edition out of print I might want to sit on that project a bit longer.
What's been even more missing is the original story itself in an English translation. There's been faithful editions of the classic Chinese legend The Water Margin — a/k/a Suikoden in Japan, or Outlaws of the Marsh in its recent English translation — but Hakkenden remains untranslated. Pieces of it have shown up here and there, as Wikipedia indicates, but never the whole thing.
Takizawa's original has been retold any number of times — even by Guin Saga creator Kaoru Kurimoto, if Amazon is to be believed. On my last trip to Book-Off in the city, I bumped into Takaya Hama's retelling (with some amazing illustrations by Takato Yamamoto), so it's not as if we have a dearth of possible versions to work from. I suspect it's just one of those tasks that no translator has yet opted for given the esoteric nature of the material. Some of the original has been posted for free on the web — it is out of copyright, after all — but a complete e-text has yet to be compiled.