Yoshiaki Kawajiri directed this in 1993 with the economy of someone who has thought about very little except how a sword moves through space and has thought about that with complete precision. Ninja Scroll does not have a great deal of interest in introspection or thematic complexity. It has extraordinary interest in choreography, consequence, and the specific logic of a fight between people who cannot be killed by conventional means. Within those parameters it is essentially perfect.
The film that circulated through VHS trading networks and early fansub IRC channels before anyone had a legal way to own it in the West. The violence is real and the film does not apologize for it. Kawajiri's Madhouse production design - the creature work, the environments, the specific weight given to every impact - remains the high-water mark of the hand-drawn action aesthetic. Before CGI made it easier and worse.