I love these 1960s samurai films from Japan. If you want to watch this online, you better do so soon. I imagine it will eventually be taken down. Here is a synopsis from the Criterion Collection website:
Years of warfare end in a Japan unified under the Tokugawa shogunate, and samurai spy Sasuke Sarutobi, tired of conflict, longs for peace. When a high-ranking spy named Tatewaki Koriyama defects from the shogun to a rival clan, however, the world of swordsmen is thrown into turmoil. After Sasuke is unwittingly drawn into the conflict, he tracks Tatewaki, while a mysterious, white-hooded figure seems to hunt them both. By tale’s end, no one is who they seemed to be, and the truth is far more personal than anyone suspected. Director Masahiro Shinoda’s Samurai Spy, filled with clan intrigue, ninja spies, and multiple double crosses, marks a bold stylistic departure from swordplay film convention.
In the 1950s, the samurai film evolved definitively from the early narrative and visual conventions that had restrained it. Although they often worked outside the genre, Akira Kurosawa and Masaki Kobayashi were the principals in a first wave of directors who redefined chanbara—a term taken from theater that refers to any drama, including a movie, that features realistic sword-play—culminating with the release of Yojimbo (1961) and Harakiri (1962). In the years immediately following those films, a second wave of chanbara innovators emerged, directors who were children during the decade of imperialism leading up to World War II and who approached questions of tradition and authority from an even more critical perspective. Under a host of new graphic influences, from television drama to more realistic detail in manga (comic books), these directors took the thematic and stylistic innovations of Kurosawa and Kobayashi to new extremes. As were many postwar moviegoers, the period characters created by these filmmakers were estranged from their environment—Japan’s feudal society—so that violence in these films functions both as existential definition of a protagonist’s being and as the most direct method for expressing his (or, on rare occasions, her) oppressed relationship to that society.