Sadako Yamamura

Sadako Yamamura is the main antagonist from the horror film series Ringu, which is in turn based on a trilogy called Ring written by Koji Suzuki. She had immense psychic powers, including the ability to kill someone just by wishing it. Her character was the main influence of Samara Morgan who was featured in the American remake of Ringu.

History
In Oshima Island, there was a psychic named Shizuko Yamamura, who was always considered strange by the other inhabitants in her home island as she would sit on the beach and stare at the ocean for hours. In reality, Shizuko was talking to a sea demon, who shortly after impregnanted her with a strange daughter named Sadako who possessed strange abilities. Shizuko intended to abandon Sadako at the beach but Sadako was still there even when the waves washed her away, leaving her with no choice but to raise her as her own.

Shizuko had also predicted the eruption of Mt. Mihara, the island's volcano, with her psychic powers. Hoping to make money off of Shizuko, her cousin leaked this to the press, and Shizuko became famous overnight. This attracted the attention of Dr. Heihachiro Ikuma, a university professor from Tokyo who wanted to prove the existence of ESP. He sailed to Oshima and visited Shizuko, where they began a love affair and eventually married each other. Noticing that Shizuko was pregnant, Ikuma was assumed to be Sadako's father. After Sadako's birth, Ikuma took her and her mother to Tokyo to use their powers as evidence for his experimental studies on the existence of ESP. A few years later, Ikuma decided to hold a public demonstration of Shizuko's powers, with members of the press present. Ikuma and Shizuko proceeded with the demonstration, while Sadako watched from backstage. Shizuko never once failed, but the demonstration was interrupted by a reporter who stood up and declared that Shizuko was faking her abilities.

This started an uproar, with other observers joining in the declarations of "fraud", "freak" and "fake." Enraged by the treatment of her mother, Sadako snapped and used her powers to kill the reporter who initially caused the uproar by giving him a heart attack., leaving his face gruesomely distorted. After the demonstration, Ikuma was fired from his university. He took Sadako with him to his home on the Izu Peninsula, while Shizuko returned to Oshima, eventually killing herself by leaping into Mt. Mihara, an active volcano during the time. Ikuma, who loved Sadako as his own daughter, wanted her to have a normal life, but he realized that Sadako splitted into evil and good "clones" of herself after the failed demonstration. Ikuma imprisoned and drugged the evil clone of Sadako so that the evil clone will never develop during puberty. Meanwhile he took great care of the good clone of Sadako and allowed her to live a normal life. In order to overcome her anxieties and nightmares which Sadako often experienced after the suicide of her mother and her evil clone constantly tormenting her, Sadako joined a local acting school in Tokyo as recommended by her psychiatrist.

During her time in the acting school, Sadako's beauty and charisma charmed most of the members of the acting troupe, especially the sound manager Toyama, whom Sadako fell in love with. However, the members of the acting troupe (except for Toyama) began to fear and bully her after discovering her powers. Her powers also accidentally initiated a curse via a sound tape, which killed one of the troupe members after listening to the sound tape. The evil clone of Sadako began to taunt the good clone of Sadako which led her to be more alienated and drive her into killing her psychiatrist during a live performance of a play whilst he tried to calm her down. This led Sadako to be attacked and eventually killed by the angry mob of the troupe members led by the fiance of the reporter who was killed during Shizuko's demonstration.

The angry mob later soon realised that there was an evil side of Sadako and wanting to save themselves from the curse that Sadako unleashed, they arrive to Izu Penisusla to kill the evil clone. However, the dead body of Sadako's good clone being in close proxmitiy to her evil clone allowed both of them to merge into a freakish and maniac monster that Sadako was most well-known for with long black hair concealing their faces. In their merged form, Sadako accidentally kills Toyama off-screen and goes on a murderous rampage against all of the members of the angry mob, who all died of a sudden heart attack. Two remaining members attempt to hide in Sadako's childhood home but Sadako approaches them and both members shoot themselves in order to avoid being killed by her as Sadako watches.

The good clone of Sadako eventually recovers in her home but she realises that Ikuma is planning to drug her with poison. Sadako escapes into the forest outside but Ikuma bludegeons her in an attempt to stop her powers from harming anyone and throws her body into a nearby well. Ikuma tearfully breaks down and looks at the body of his daughter in the well one last time before he seals it with a stone lid. Sadako however remained alive for 30 years inside the well until her uncle retrieves her body from the well and is summoned to identify her.Meanwhile, a set of rental cabins were built over the well and inside, it contained a blank videotape where Sadako psionically transferred her twisted and pessimistic views of her own life into the videotape. The videotape became cursed and anyone who watched it would be killed by Sadako's vengeful ghost 7 days after initially viewing it. The viewer also receives a phonecall notifying about their 7 day deadline but this only happens if the viewer watched the videotape in the cabin.

In the form of her vengeful spirit, Sadako usually kills her victims by crawling out of her victim's TV screen and revealing her rolled back eye to them in order to frighten them and ultimately kill them via a heart attack. If her victim is not nearby a TV, she can still appear through any reflective surface and frighten them to death or in some versions, drive them insane to cause them to commit suicide. Her victims often die immediately and a distorted facial expression of fear is left permanently on their faces in a similar fashion to the reporter that Sadako killed when she was still alive.

Throughout the films and novels, it appears that Sadako has a significant influence over the protagonists' lives regardless of whether or not they have watched the cursed videotape or not. The widespread impact of the cursed videotape in Japan has also caused her to become a modern day version of the bogeyman, especially amongst teenagers who have heard about the legend surrounding the tape. Being exposed to Sadako's presence (usually a bystander who witensses Sadako killing her victims on their 7th day) also leads people to develop psychic abilities which can have the potential to harm or kill others in a similar fashion to how Sadako usually kills her victims.

Scientists and doctors are also drawn into Sadako's mysterious supernatural abilities but their experiments with her abilities often lead to unfortunate and fatal circumstances for the other characters such as Masami in Ring 2 where she was killed after having an intense mental overload during a medical experiment that tested her ability to burn images onto surfaces after being exposed to the presence of Sadako when she killed her best friend Tomoko after watching the cursed videotape.

In the novels, Sadako creates a virus known as the "Ring Virus" in the cursed videotape since she will "live on" in it, as long as her DNA merged with that of a strand of the smallpox virus still exists. This was to ensure her that she will reproduce, which she cannot do herself due to being intersexual, or in other versions, to find a host in order to be reborn. In some incarnations, the "Ring Virus" is simply treated as a mysterious phenomenon rather than a biological virus; in these versions, she is portrayed as having created it to wreak vengeance on humanity. Sadako's goal is to make mankind aware of her suffering in life and uses the videotape through various means to achieve this.

Sadako vs Kayako
Sadako is featured as the main antagonist in Sadako vs. Kayako where she was lured into fighting off against another rival vengeful ghost in order to end both of the evil curses that have both entities have inflicted upon the living world.

With Yuri (protagonist of the film) and Natsume's attempt to save themselves from Sadako's curse ended in disaster as Natsume's attempt to rid the said curse by uploading the tape's contains to internet wind up gave Sadako tons of victims on her list and the exorcism provoked Sadako to slaughtered miko who assisted them, they resort for Keizo Tokiwa's aid whom suggested that they must pit Sadako against another powerful vengeful spirit. Keizo then suggested that they chooses Kayako to combat Sadako, as coincidently Keizo has discovered Sadako's lair which none other than her own house and found that Suzuka would inflict herself with Kayako's curse.

Just as they began to carry out this plan, Kayako has began her own rampage by slaughtered Suzuka's family whom tries to help their daughter. Keizo distracted Kayako long enough so Yuri and Suzuka had the opportunity to summon Sadako for them via the cursed tape and set up a television as medium for Sadako to enter. Predictably, as Kayako and Toshio emerges, Sadako launched her hair to pulled Toshio into TV and immobilized him inside before proceed to fight Kayako in brutal fight.

Kayako pounches Sadako and seemingly defeat her offscreen, but just as she goes for the girls, Sadako recovers and ensnared her with her hair before impaled some of them to the opposing ghost's eyes and mouth to tear her into bloody mess, seemingly defeated her. By the time Sadako resume the chase, Kayako has already regenerated from her own remains before resume the fight. During this point, Keizo tossed Sadako's cursed tape on Kayako whom proceed to broke it, but interrupted by Sadako whom resume the fight.

Due to the fight ended in stalmate and began to compete on the common target, Yuri decided to sacrifice herself by jumped to the well that they used to seal the fighting spirits in case of this would happened. Just as Yuri entered, both ghosts inadvertly crashed on each other due to blindly lunged on their target, and explodes upon impact. Their essences then fell on Yuri just as Suzuka sealed the well and Keizo was killed by the blast due to protecting his assistant Tamao.

Just when the horror finally seems to be over, the seal is suddenly ripped off, revealed that the previous explosion that seemingly killed both spirits turned out given birth to a new, stronger entity called Sayako where it composed of Sadako and Kayako's essence that possessed Yuri. The hybrid ghost then proceed to approach Suzuka, just as Toshio, whom recovered from the ambush began to approach Tamao.

Trivia

 * Sadako's character is very similar to Carrie White as both are outcasts in society and struggled to fit in due to their potentially deadly supernatural abilities. They also have been isolated by members in society and have been sent to schools to "fit in". While staying in their schools, they have also developed feelings for a man who was well-liked amongst the crowd but their powers eventually go out of control, which leads to their boyfriends' deaths and they also go on a rampage to kill their tormentors. Both characters have also been abused and eventually killed by their parents and they both were restless beyond their grave after their cruel death.
 * She is also similar to Kayako Saeki as they are both onryo spirits that were killed by a relative, causing their spirits to want the whole world to understand what they went through. Both also have victims who turn into onryo spirits themselves (in Ringu, after Tomoko was killed by Sadako, she became an onryo spirit who lured her cousin Yoichi to watch the cursed videotape).
 * Both Sadako and Kayako even featured in crossover film Sadako vs. Kayako (see Sadako vs. Kayako section above) together as opposing antagonists where in their confrontation, aside being similar, both are equally powerful.
 * She is also very similar to Carmen Winstead as both have been thrown into an underground place (Sadako-well, Carmen-manhole) and manipulated technology in order to seek revenge and kill anyone who refuses to believe them or pass their stories to others.
 * Her name means "chaste" (free from any sexual intercourse) in Japanese which may hint to her inability to reproduce due to her Testicular Feminization Syndrome and her obsession of procreating (this is explained in the original novels).
 * Sadako Yamamura was based on the character Okiku from the Japanese folkloric tale caled "Banchō Sarayashik", who was the servant of a samurai, who eventually killed her by throwing her in the well as she rejected his amorous advances. She became a vengeful ghost like Sadako who haunted the samurai day and night.
 * The concept of Sadako's good side and evil side and both sides merging together near the end of the plot is similar to Alessa Gillespie, who also splitted her souls into a good version of herself and an evil version of herself. Adding onto that, both characters originated from Japan, both have unknown fathers, both have mothers who had contact with demonic entities, both possess supernatural abilities that cause them to be alienated, both are considered to be demonic incarnations (Alessa was accused of being one whilst Sadako was literally one since her father was an actual sea demon), both were attempted to be killed by members of society who feared and ultimately outcasted them because of their powers and both have initiated a powerful curse that holds immense control over the settings that the characters live in in both films.
 * Sadako is based on the life of early-20th century psychic Sadako Takahashi, an apparent practitioner of nensha, the art of projecting images onto film by thought alone. In 1931 Takahashi was studied by psychologist Tomokichi Fukurai for his book "Clairvoyance and Thoughtography".