Kayako, along with the onryo from the Ring series, Sadako Yamamura. Through a rumor, it is explained that Kayako was repeatedly stabbed to death by her husband before he drowned their son, Toshio, and hung himself. Ever since, Kayako's and Toshio's spirits haunt their household, killing anyone who sets foot inside.

The Grudge (Ju-On) and Ring movies are works of fiction and are not based on actual events. However, they do draw upon Japanese folklore and urban legends, which have been a rich source of inspiration for Japanese horror films.