Hey look - another Hollywood butchering of Japanese history and folklore. 47 Ronin is a fantasy take on the tale of the Forty-seven Ronin (四十七士), adding witches and giants to the storyline, as well as a gaijin in the form of Keanu Reeves. The film also stars Cary-Hiroyuki Tagawa (Shang Tsung in Mortal Kombat, Heihachi in Tekken), Rinko Kikuchi (Chieko in Babel, Mako in Pacific Rim), Hiroyuki Sanada (Ujio in The Last Samurai, Shingen Yashida in The Wolverine), Tadanobu Asano (Genghis Khan in Mongol, Hogun in Thor), Kou Shibasaki (Mitsuko in Battle Royale), Jin Akanishi (former KAT-TUN member), and Rick "Zombie Boy" Genest (model known for his skeletal tattoos).
Might as well call it "The Last Samurai Airbender".
Official Site
And just to spare Duke the time of posting...