Plot

A mysterious and vengeful spirit marks and pursues anybody who dares enter the house in which it resides.

In Japan, when the volunteer social assistant Rika Nishina is assigned to visit a family, she is cursed and chased by two revengeful fiends: Kayako, a woman brutally murdered by her husband and her son Toshio. Each person that lives in or visits the haunted house is murdered or disappears.—Claudio Carvalho, Rio de Janeiro, Brazil

Rika is a young woman in Japan who takes care of an old woman named Sachie. While she is at the house, Rika finds a young boy named Toshio. She eventually finds about a curse, that anyone who enters the house will be killed by the spirit of Kayako. Rika must get herself out of the curse before it's too late.—Anonymous

It looks like a normal, everyday house, but the atmosphere about it is anything but. Something happened here once... no, even now there is a terror here, born of a spirit that possesses this place. The various supernatural experiences undergone by the different owners of the house, unaware of the horrible events that have taken place here, mingle across time, and the true form of the terrifying, invisible "Ju-On" that nests in this house becomes clear...—anonymous

A very evil curse and vengeful spirits seem to linger upon a house where the horrific murder of a woman and child took place and anyone who sets foot inside the house is marked for a terrifying haunting which will not rest. One by one, those guys who have been tainted by the house begin to die, and nowhere is safe.—Dismal Angel

A few years after the events of Ju-On: The Curse and Ju-On: The Curse 2, the Saeki family home has new residents: the Tokunaga family, consisting of salary man Katsuya, his wife Kazumi and Katsuya's demented mother Sachie. When Katsuya goes to work as usual on the day of his sister Hitomi's birthday, Kazumi is haunted at home by the ghost of Kayako Saeki. She lies listlessly on her bed when he returns and does not respond to his attempts to get her attention. Suddenly she appears to suffer some sort of epileptic seizure and dies. A foreign entity (the spirit of Takeo Saeki) then takes possession of the horrified Katsuya. When Hitomi shows up to celebrate her birthday with the family, Katsuya behaves distantly and hostilely toward her, ramblings about a child that isn't his, to her confusion, and sends her away again. He then carries Kazumi's body to the attic, where Kayako's ghost awaits him.

A few days later, the geriatric nurse Rika is called to the Tokunagas' house, where she finds Sachie, who seems completely beside herself. While Rika is cleaning up the house, she hears a cat meowing from a closet upstairs. When she opens the closet she sees them, but also a little boy named Toshio, the Saeki's son. She can't find out from him what happened to the Tokunagas or where he comes from and reports this to her superior Hirohashi on the phone. When Hitomi calls afterwards, she doesn't answer and only hears her angry demand for an explanation for Katsuya's strange behavior on the answering machine. Rika turns back to Sachie, who is suddenly attacked by a shadowy figure. Rika faints from shock.

At the same time, after making her call, Hitomi is haunted by ghostly apparitions in the office building where she works. She alerts a security guard and sends him to the ladies' room, where she was last harassed by a mysterious figure with long black hair. In his office, she uses a surveillance camera to watch him being pulled into the toilet room by a shadowy entity when he arrives, and then flees to her office in panic. But she isn't safe there either. As she hides under the covers, Kayako's ghost appears underneath and disappears with her.

The next day, the unconscious Rika is found by Hirohashi, who alerts the police. Detectives Nakagawa and Igarashi find Katsuya and Kazumi's bodies in the attic and later learn of Hitomi's disappearance and the death of a security guard in their office building. Meanwhile, Rika is haunted at home by the ghosts of Toshio and Kayako. Nakagawa and Igarashi contact former police officer Toyama, who investigated Saeki's murder but is afraid to return to it. When they play him the videotape of the security guard's death, he is also haunted by a shadowy figure and flees in panic. He tries to burn down the Saeki house with gasoline, but is distracted by a vision that shows him his teenage daughter Izumi, who enters the house with her friends a few years later, but leaves them alone. The three friends left behind are killed by Kayako (this is probably the last chapter of Ju-On: The Curse 2). Izumi also seems to notice her father when these two time levels overlap. After the vision disappears, Nakagawa and Igarashi appear who want to dissuade Toyama from his plan. However, all three are surprised by the ghost of Kayako. Toyama manages to escape, while Nakagawa and Igarashi, frozen in shock, are killed by Kayako.

An indefinite time later, Rika, who has come to terms with the terrible experiences, goes back to work as a geriatric nurse, but is suddenly harassed by ghostly apparitions again. When her friend Mariko, an elementary school teacher, tells her over the phone that she went to the Saeki house because Toshio is listed as one of her students but never showed up in class, Rika comes to her rescue. However, she arrives too late and can only watch helplessly as Mariko is pulled into the void by an invisible force. As she is about to leave the house, she notices, to her confusion and dismay, that when she looks into a mirror, Kayako appears there instead. She becomes aware of Kayako and Toshio's previous appearances as attempts at contact and attempts to communicate with them. Kayako's ghost now appears again and crawls down the stairs, covered in blood and groaning in agony, which now evokes sympathy from Rika. But then Takeo's ghost also appears and approaches Rika realizes too late that he is going to re-enact his wife's murder and that she has been chosen to take Kayako's place. He kills her before she can escape.

Numerous posters with missing people can now be seen in the seemingly deserted streets of Tokyo. Meanwhile, Rika lies in the attic of the Saeki house, with long black hair and wrapped in plastic like Kayako was when she was murdered. She opens her eyes and, like them, emits a death rattle, which indicates that the cycle begins again and she too becomes an onryo, a spirit of vengeance.

A few years later, Toyama also died and the older Izumi visited the Saeki house with her friends as a test of courage. She suffers from the guilt of leaving them behind and behaves absently towards her other friends. When they receive photos from school trips, the eyes of Izumi and the missing friends are blacked out. The other two friends visit Izumi, who has now completely isolated herself and become paranoid. After they leave, Izumi has a dream vision of her late father Toyama, who does not respond to her attempts to talk to him. When she awakens again, she is haunted by the ghosts of her friends. Izumi tries to escape in panic, but is eventually grabbed by Kayako, who drags her into the afterlife, where Izumi keeps her father company.