Kamui no Ken, which I saw for the first time in the abridged version entitled "Revenge of the Ninja Warrior" is a historical drama story about a half Ainu, half Japanese boy living in the turbulent period of the Tokugawa era, the Boshin War and early part of the Meiji era. That setting is the backdrop for the story, and it's one of mystery, intrique, betrayal and vengence.
He's framed for the murder of his mother and sister and forced to flee from his village and is taken in by a monk named Tenkai whom gives Jiro the task of training to become a ninja.
The art style is very well suited for the anime and the ninja fight scenes are done quite well. The musical score is truly something else, it's something like a fusion of 80s rock and traditional Japanese music and in a lot of scenes it does a really good job of setting the mood.
Over the duration of the story, Jiro learns about the (then) small world of feudal Japan and the remainder of the modern world. He even meets some significant historical figures along the way.
One of the themes touched on by this movie is the question that the Japanese likely asked themselves during this era.. that is, "If we become a modern nation, will we lose something in the process of doing so?"
If you're into action anime, you'll enjoy this one. If you're into historical drama, you'll enjoy this one.