The Hidden Blade (Kakushi-ken: oni no tsume)

A lower-class samurai, named Katagiri, secretly loves Kie, a servant in his family's household. Eventually their perception of honor forces them to part, and he must turn his focus toward a disheartening task. His old friend, Yaichiro Hazama, has been fomenting rebellion against the government, and Katagiri must hunt him down and kill him.