Lady Ninja Kasumi 6: Yukimura Assasination (2008)

The story revolves around a man named Takuma who works under the legendary samurai Sanada Yukimura teaching a secret technique called “Kakure Musou”. However, Sanada won't allow Takuma to actually fight for him because he's hampered by a painful disease of the eyes. It's the worst kind of humiliation for a warrior like Takuma. A woman, played by Asami (Sukeban Boy, The Machine Girl), eventually makes a special medicine that helps him recover from his affliction. Meanwhile, Kasumi is sent to investigate a bandit who intends to assassinate Sanada. As the threat of assassination draws closer the shocking truth is exposed and Kasumi is forced to face off against an unlikely betrayer.