For those confused as to why people are calling the Sadako parodies, "ring girls". (I was confused and did some googling)
"Sadako Yamamura (山村 貞子 Yamamura Sadako) is the central antagonist of Koji Suzuki's Ring novel series and the film franchise of the same name. Her surname combines the Japanese words for "chaste" (sada) and "child" (ko). Sadako's fictional history alternates between continuities, but all depict her as the vengeful ghost of a psychic who was murdered and thrown into a well. As a ghost, she uses nensha, her most distinctive power and weapon, to create a cursed video tape that will kill whoever watches it exactly one week later unless the tape is copied and shown to another person, who then must repeat the same process"