The one armed swordsman of the title is a foreigner from China who crosses the local samurai and becomes an outlaw. Unique story or not it interestingly unfolds that the one armed man barely speaks the language and so fails to communicate with Zatoichi. Yet, almost inevitably, they are drawn into fighting each other, which is a common occurrence I used to read in comic books.
In oriental cultures everyone calls each other Auntie or Uncle, which also adds to the confusion, the costumes don't help with character recognition but are fitting for the period, which is a brutal class system. I would have enjoyed it more with either an English narration or better introduction of key characters like they used in the superior Water Margin, previously mentioned.
The director fails to capture any comic moments mentioned on the video packaging. In fact, the whole tale is rather sad and dark like some modern western action thrillers such as The Yakuza (1975), or even cult eastern film, Shogun Assassin (1980), but without the gore of those masterpieces. Having stated it was hard to follow, this improves on the second viewing and is definitely a good addition to any video collection.