Chiemi's boyfriend breaks up with her, telling her that while she tried to look her best for him, he still isn't satisfied and believes that they don't belong together. When she returns home, her sister, Eri, greets her, telling her that their house has mice in the attic. Eri notices that Chiemi is depressed, but doesn't know why.
While burning a picture of herself and her ex, Chiemi remembers back when he asked her to grow her hair out for him. She then falls asleep crying.
The next morning, Chiemi wakes up to find a dead mouse entangled in her hair. While washing it out, she decides once and for all to cut it off. Later, while Eri goes to find scissors to give Chiemi a haircut, she and her mother hear Chiemi screaming. When they rush upstairs, they find her decapitated body lying on the floor, with the head having vanished. The police are called, but no leads are found.
A week later, Chiemi's ex is awakened by a phone call with no one answering. He feels responsible for causing her death, believing that she committed suicide. He then starts hearing the sound of grinding teeth, followed by another phone call.
Sometime later, Eri asks her father for a flashlight so that she can check the attic for mice. Eri's father insists on going to check himself, while Eri warns him of his heart condition. After a while, Eri's father doesn't answer any of her calls. She goes to check on him, only to find him slumped against the wall, dead of a heart attack. When she looks to see what caused him to die, she finds Chiemi's head, suspended from the rafters by its hair, which has grown to a tremendous length. Eri tries to take the head down, only to find the hair is covered in blood. The hair then opens the head's eyes and it starts grinding its teeth. It then unhooks itself from the rafters and slithers out of the house. Eri realizes that her sister's hair came to life and killed her because it didn't want to be cut off. The head slithers off to Chiemi's ex's house, where it torments him by slowly coming through the cracks in the walls.