Ninja, a Band of Assassins
忍びの者 (original)
Warlord Oda Nobunaga seeks to unite a fractured Japan. A young man trained in the arts of ninjitsu is manipulated by a ninja master into attempting to assassinate the warlord before he completes his task.
Starring Raizō Ichikawa, Yūnosuke Itō, Shiho Fujimura, Katsuhiko Kobayashi, Saburo Date, Kō Nishimura, Kyōko Kishida, Reiko Fujiwara, Chitose Maki, Takeshi Katō
Watch "Ninja, a Band of Assassins" on Kanopy released in 1962. It's a drama and action & adventure movie, and has a rating of 6.9 out of 10 from Imdb which is usually fine for this kind of movie.