The film is set in the mid-fourteenth century during a period of civil war. The movie opens with two wounded soldiers escaping from a battle. They are suddenly killed by two women with spears in the tall grasses, who then strip them of their weapons and armor.
Later the women trade the armor and weapons for food with a merchant named Ushi. The older woman asks a returning soldier named Hachi about her son, who is the husband of the younger woman. He tells them that he was killed after they deserted.
Two soldiers are fighting and when one kills the other, Hachi kills the one left. Hachi and the two women then strip the men. Hachi then trades the spoils for food and sake. At night the younger woman goes over to Hachi's place. The older woman soon figures out what is going on. She doesn't want to lose the younger woman to Hachi and end up alone.
A lost samurai shows up wearing a demon mask. He wants the older woman to show him the way out, but she leads him to his death. She then steals his possessions and his mask. Under the mask she finds the samurai's face is disfigured. That night the old woman dons the demon mask to scare her daughter-in-law away from Hachi.
When Hachi goes back to his hut he is killed by a stranger. The older woman then discovers that because the mask got wet she can't take it off. She has the younger girl help her and promises not to interfere with her and Hachi. When the mask comes off her face is disfigured and the younger girl runs thinking she is a demon. The film end with the older woman chasing after the younger one.
Overall, a very good movie that is really well filmed. It is in black and white but shading and lighting are used really effectively. Story is just OK, but the overall tone and look are really well done.