Todo is a rich businessman who is very demanding of his children. All three suffer from unexplained headaches that the doctor dismisses as migraines. After the family's eldest son commits suicide, Todo begins putting pressure on his second son Eiichi, who also later kills himself. Todo says that the family has a long history of suicide, and is angry that he could not break the "curse" by becoming successful.
Eiichi's friend Tsukasa is suspicious, remembering that Eiichi used to get headaches and do reckless things that he later didn't remember. Eiichi's sister Miho also suffers memory loss, and her personality has begun to change: she is now much colder and enforces her father's rules. One day Todo invites Tsukasa to a theme park to keep Miho company. At the park, Miho gets another headache and soon starts to behave strangely. Her eyes glaze over and she first tries to jump out of a moving ride, then jump off a building. When Tsukasa runs to get Todo, Todo's eyes have taken on the same glazed look.
Miho continues to have headaches and violent fits. Her father orders her not to date boys, and is angry when he finds that a classmate wrote her a love letter. Subsequently, the boy is pushed down stairs and seriously injured; Miho realizes that she did this herself. Her headaches and strange behavior are caused by her father possessing her body. When his sons became too troublesome, he caused them to commit suicide; and now that his wife is expecting another baby, he wants to kill Miho.
Miho tries to tell Tsukasa what's happening to her, but is possessed again by her father. In Miho's body, Todo throws Tsukasa down the stairs like the other boy and warns him to stay away from her. Tsukasa arranges for Miho and her mother to stay with his aunt, but as they are leaving his house, Todo appears. He succeeds in possessing Miho but Tsukasa holds him off. Mrs. Todo decides she wants a divorce; and leaves with Miho. Todo explains to Tsukasa that he always had to work hard and wasn't able to have any fun when he was young, so he learned to possess his children's bodies as a way of living through them. He didn't intend for it to go this far. Tsukasa offers the use of his body but Todo says it only works with his own children. He has realized he must let Miho go.
The following day, Todo goes to the amusement park and enjoys the rides by himself before jumping out of the Ferris wheel to his death as he tried to make Miho do.