This movie rates as one of my all time favourite top 10 movies. Many people seeing it for the first time and knowing little about many of the themes in the movie probably won't understand why I find it so enthralling so I will try to explain...
The movie is very rich in historical detail and cultural insights, and while it has a few minor anachronisms, they are completely forgivable. The story is a retelling of the famous duel between the Monk Benkei and the young Prince Yoshitsune on Gojo bridge. During the fight according to legend Yoshitsune bests Benkei and the monk becomes the prince's loyal retainer. This movie is a revision of that story however and involves war, dark prophecy, and political maneuvering.
One of the main themes in the movie is "Mappo", which is the prophecy by the Buddha that after 1000 years his teachings would fail and the world would fall into chaos. It was believed in Heian Japan, after the eruption of Mt Fuji and the civil war between the Taira (Heike) and the Minamoto (Genji) that the world would fall into anarchy and everything would collapse. It is a time of demons.
Next you have the way in which the movie resolves the issue of Yoshitsune's sword training by the Tenku (Raven Goblins) of Karuma. Defeated clans often escaped into the mountains and disguised themselves as demons to scare the locals off. This is said to be where ninja clans began historically. Yoshitsune's depiction in Gojo nicely accommodates all of this.
Then there is Benkei, and the various strains of Buddhism depicted, including a lot of Esoteric Buddhism of the Shingon sect. These are all depicted quite accurately, and just to add a little extra, the movie manages to convey the power of meditation and Ki energy in a way that makes it integral to the story, i.e. it uses magic realism to add an extra dimension to the film but does it in such a way as to make it tactical and menacing.
All-in-all it is filled with fascinating tidbits and rings surprisingly true-to-life for the period. The scenery and the costuming are also completely unmissable and very authentic. The soundtrack is great, very brooding and ominous. I also thought that the actual acting performances were surprisingly good. Benkei is a great brooding anti-hero, Shanao (Yoshitsune)is depicted as a young man testing his limits and growing increasingly drunk on his own power, and Tetsukichi the scavenging sword-smith makes for and interesting depiction of the "common man" and his less than flattering opinion of the killers who fancy themselves his social betters.
As to the plot, to see why it is so good, I really suggest you dig up an old book on Japanese history and see how this retelling turns an almost lighthearted Robin Hood vs Little John story into a gory tale of intrigue, violence and infernal karma.
