Yes, Virginia, there is an original "47 Ronin" story, just not the same one in the new movie starring Keanu Reeves.
In the film, set in Edo-era Japan (1603-1867), an evil warlord kills the master of 47 samurai. These warriors are now "ronin" -- a mark of shame, as it implies these warriors failed to protect their master. They vow vengeance and seek the help of the previously rejected Kai (Mr. Reeves), who leads them in battle against all sorts of fantastical threats.
That sort of special-effects extravaganza is what Hollywood does better than anyone else -- but it's not the same story Japanese kids have been reading for generations.
That story is one of Japan's most important and legendary events. It's the sort of story that is imbedded in a culture's DNA, like the Western in America, for example.
In the Japanese tale, Lord Asano is driven by insults to attack a rude member of the emperor's staff. This is an unforgiveable sin, and the lord is asked to commit ritual self-execution. The death of their master means Asano's 47 samurai are ronin, who are now not only without honor, but also homeless. Even more galling, the man who insulted Asano is still alive, and receives no punishment.
Saying much more would be a spoiler, but if you want to read the story for yourself, "The 47 Ronin: A Graphic Novel" ($14.95, Shambhala), adapted by writer Sean Michael Wilson and artist Akiko Shimojima, was released in November. Or you can wait until February, when Dark Horse will publish a hardback version by DH Publisher Mike Richardson and artist Stan Sakai. As comics fans know, Mr. Sakai has been blowing away audiences for years as the writer/artist of the samurai epic "Usagi Yojimbo."
With either book, you can enjoy a little insight into Japanese culture, along with an absorbing story.