Kayako spends her childhood with her sister and mother, an Itako (Japanese exorcist) who uses Kayako to "eat" the evil spirits she drives away from her patients. Kayako’s sister Naoko was spared of this treatment. This marks young Kayako for the rest of her life, making her a target for gossip and cruelty. Kayako didn't seem to have a father-figure in her life in the American films. Unlike in "Ju-on", Kayako didn't lead a normal childhood and her mother was highly abusive. Therefore, the primary reason for her becoming an Onryō in "The Grudge" is because of the malevolent spirits she was fed by her mother, and not purely because of the painful nature of her death.