Ring (リング, Ringu) is a series of horror novels written by Koji Suzuki. The novels were initially a trilogy, consisting of Ring, Spiral, and Loop. A short story collection called Birthday was released shortly after, introducing extra stories interconnecting the trilogy. Two further books, S and Tide, were published in 2012 and 2013, respectively. The novels revolve around a curse, embodied within a videotape, unleashed by Sadako Yamamura, the ghost of a psychic who was raped and murdered before being thrown into a well. Though the curse was initially presented as a supernatural force, it is eventually revealed to be a cataclysmic virus which Sadako utilizes for her own misanthropic ends. The success of the novels led to the release of numerous film adaptations in Japan, South Korea, and the United States. Source: Wikipedia (en)