The movie introduces Kayako's sister Naoko, who is portrayed as a vengeful spirit seeking retribution for the wrongs done to her family. However, unlike the previous Grudge movies, the final scene does not explicitly show Naoko creating a new curse or spreading her vengeful energy.
The movie hints at the possibility of a continued or reborn grudge, as it emphasizes the interconnectedness of the characters and their involvement with the cursed house. However, it also leaves room for viewers to consider that Naoko's anger has been appeased or that the curse has been broken.
Ultimately, the film's ending is open to interpretation, allowing different fans to draw their own conclusions about the potential for a new grudge or the finality of the story.