Sword of the stranger is a film well regarded for its incredible action animation. I am sure many over you interested in this film, will have seen the amazing Yutaka Nakamura sword duel at the end of the film. It is by far the best sword combat I have seen in animation.
As an action film the story is passable. It's a simple tale about a mysterious boy, Kotaro, attempting to escape from the Chinese soldiers. After his escape, he happens across a nameless (Nanashi) ronin who agrees to act as a body guard for him, during his travels. Over the course of the film, the 2 come to share a close bond like that of a father and son or perhaps older and younger brother, which results in Nanashi saving him in the end; not for profit but for love.
While I enjoyed the interactions between these 2, I think the story suffers from having far too many characters. There is more than half a dozen major villains in the story, from 3 different factions. Side characters form alliances and betray one another, which would be an interesting idea in theory, but the story never fleshes out their personalities, homelands, histories etc. So you end up watching these characters you know nothing about kill each other. It's cool to watch from an animation stand point but means very little narratively. The time wasted on these side characters could have been used to further develop the relationship between Nanashi and Kotaro, to flesh out their characters and perhaps to flesh the main antagonist more.
As it is now, Nanashi is basically a generic ronin: quiet, reserved, standoffish, with a mysterious dark past. Kotaro on the other hand is the generic spunky kid character. They're both functional, perhaps even likeable but more could have been done to make them stand out. It would likewise explain why Nanashi opens up to Kotaro so suddenly.
The villains, likewise, are extremely flat. The Chinese characters are essentially drones following the emperor's wishes. The emperor isn't so much a character as much as he is a plot device to kick the story in motion. He's just some guy we're vaguely made aware of that believes he can become immortal by consuming Kotaro's blood. Why? Who knows. The only villain that stands out in this series is Luo Lang the European mercenary. He is likewise a flat character. His purpose in life is essentially seeking a worthy opponent. He's fun to watch because of his controlled yet extremely aggressive combat style and his cool design but outside of that, there's really nothing to him.
The world isn't really fleshed out beyond occurring in a vague version of Japan during the Ming Dynasty (perhaps the Sengoku period for Japan). I think this would be fine if the plot and characters were more tightly written but without that, the bland setting is more egregious as it does nothing but act as nice background art for the story.
The story meanders a lot during the mid section. The introduction immediately establishes the threat and the main characters however afterwards, very little occurs to move the plot along until Kotaro is captured once more. The beginning and ending of the film are quite enjoyable however, very little of substance occurs in the hour or so in the middle of the film.
If you enjoyed this film and are looking for an alternative, I would recommend Seirei no Moribito. It has a similar premise but with more fleshed out world and characters.