Loop (ループ, Rūpu) is the third in the series of Ring novels by Koji Suzuki.
The story revolves around a simulated reality, exactly the same as our own, known as the Loop: created to simulate the emergence and evolution of life. It is in this alternate universe that the events of the previous novels, Ring and Spiral took place.
The story revolves around a medical student named Kaoru Futami. His father, Hideyuki, contracts a deadly disease known as Metastatic Human Cancer (MHC). This is a terminal cancer that involves all forms of organic life: humans, animals and plants. Events lead his father to tell Kaoru more about the LOOP project he worked on. The LOOP project is essentially a virtual reality simulator which is meant to represent the emergence of life and how the world most likely evolved. It is known that almost everyone who was involved in the LOOP project has died of the same cancer.
Kaoru, now 20, ends up studying medicine taking tutoring on as a part-time job. He often likes to relax in the public pool where he first meets Reiko and her son Ryoji. He later meets them at the Cancer Ward where his father is being nursed. Reiko asks him to tutor her son, who also has the virus. Kaoru takes on this challenge mainly because he falls in love with Reiko, who is about 15 years his senior. Reiko is also a carrier of the MHC virus, much like his mother Machiko, but neither one of them actually contract the virus. Eventually, Kaoru and Reiko start to have sex with one another once Ryoji goes through Chemotherapy sessions. When Ryoji figures this out, he commits suicide by falling backwards out of a 12-story building onto the concrete. It's about a month later when Reiko and Kaoru meet one more time where she thinks she's pregnant with Kaoru's child. He also reads Ryoji's suicide note which tells him the motivation for his suicide.
Kaoru continues his investigation on the LOOP and his father asks him to meet a man named Amano. Amano, a microbiologist, was involved in the final stages of Loop before it was scrapped. He reveals to Kaoru that LOOP was a project involving a hundred supercomputers strung together with the aim to recreate life. Amano also tells Kaoru of a lab in New Mexico where another scientist might be alive. During this period he also finds out that the cancer cells all equal 2n X 3. Kaoru's mother, Machiko, convinces him to go to the desert after relating a tale of the "Ancient One" who has a thousand eyes watching.
Kaoru then ventures to this place only to find the scientist dead. However, he finds his lab and enters. The computer turns itself on and wishes him to put on a pair of virtual reality goggles and gloves. He tries them on and minutes later is sent into the Loop world. Once in the LOOP, he experiences a Native American's life who has a wife and two children. Unlike watching a movie, Kaoru actually experiences the feelings of—and pain of—the person. Eventually, his character is brutally murdered by whites. He then comes back to the real world where he has a hard time distinguishing the difference between the real world and LOOP world. In order to keep himself aware of the real world, he hurts himself and then calls Reiko, then Amano. Once he calls Amano he specifically asks for the coordinates of the events that are crucial to the LOOP evolution: the lives of Asakawa, Takayama and Yamamura. Amano pinpoints the exact coordinates of the events that take place. He also explains how Kaoru can either merge consciousness with people in LOOP or that he watch from afar like a ghost. He then finds out, in complete detail, events from the previous novels navigating from different angles. First he looks at things from Ryuji's eyes, then Asakawa, finally settling on a character named Ando who finds out the truth about Sadako.
Soon after that, he has another discussion with Amano, who knows that the LOOP's creator wanted to recreate Ryuji's death. By doing so, he could create a clone and insert him into a woman's womb. But what they forgot is that Ryuji's clone would carry the Ring Virus with his genes. Therefore, when Ryuji was reborn, the virus escaped and mutated into the MHC virus.
Desperate to find the cure for the MHC virus, Kaoru ventures deeper west into the desert only to encounter a storm that leaves him on the verge of death. He is then saved by an old man named Eliot who has purposefully crafted all the events to bring Kaoru to him. After essentially resurrecting Kaoru, the man explains what has happened, and that, Kaoru is Ryuji's clone. As a result, Kaoru has an exceptional gift of immunity to the MHC virus. In order to stop the virus from destroying the real world, Kaoru is essentially sent back to the virtual world as the one who solves the Ring virus. One of the main problems is that he cannot come back to the real world to see his father (still in the hospital) or Reiko ever again. However, in order to save them, he agrees.
Upon accepting, the old man transfers Kaoru's analyzed molecules into the LOOP where he promises that Reiko can see him. In the LOOP, Kaoru solves the problem with the help of Ando. He watches Ando's resurrected son play in the water. Once Ando leaves, Kaoru looks up at the stars wondering about Reiko.
This book, for many readers, is described as either the worst or best of Koji Suzuki's novels from the Ring trilogy and series. Many did not like the technical, pseudo-scientific language he layers into the novel, while others are dissatisfied with the ending. Despite the success of Ring and Ring 2, they never decided to make Loop, which would have been Ring 3. This is an odd choice to make because they did make a version of the fourth book Birthday. Suzuki has professed, however, that Loop was his favorite novel in the series. Out of all four books Suzuki made for the series, this is only one that was never turned into a film.
Suzuki is well-known and beloved for his horror novel trilogy Ring. This novel, however, contains the least amount of horror elements commonly found in the first two books. This may play a role as to why many readers of Suzuki's previous novels dislike the third (see above). This novel also goes into a lot of detail about scientific and literary issues such as: longevity zones and gravitational anomalies, cancer cells, AIDS, genetics, Native American culture and simulated reality.
Suzuki first wrote the novel in 1998 during a period in which many popular movies revolved around the idea of an alternate universe through simulated reality. Two good examples of this in film are The Truman Show (1998) and The Matrix (1999). In all three of these stories, the main protagonist find an alternate universe and there is a choice they need to make to stay or escape. The theme of choice and the ability to choose one's destiny then becomes paramount to the genre of simulated reality fiction.
It is not surprising either that Loop was written just before the end of the 20th century. Fears about the end of the world as via technology (Y2K) was increasing every moment. In this way, one can see Loop as a horror novel that preys upon the fear of 20th century readers. The novel also goes into some detail as to how the Ring virus itself has become a part of the real world, killing humans, plants and animals. This may also relate to fears of technology taking over human life, something many people still fear today.
Suzuki also includes Native American folklore which is critical to the story's plot. Kaoru's mother, Machiko, is an English instructor at a Japanese university with a specialty in American Culture, specifically Native American folklore. She convinces Kaoru to go to Los Alamos, New Mexico because of a story she finds from ancient folklore. From reviews of the novel, it is not a surprise that Suzuki includes Native American folklore because he often uses it in his other writing like his famous novel (Paradise).
The second half of the novel completely (in the real world) takes place in Los Alamos where Kaoru finds the Loop machine. Kaoru's first trip into the Loop is a recounting of a Native American family running towards the West. This story does not seem out of place because his wife (in the virtual world) resembles Reiko and his step-son resembles Ryoji. In this story, everyone in his family dies thus providing a motivation for Kaoru, once he returns to the real world, to prevent the same thing happening to his family.
Although not explicitly mentioned in this novel, the ideas of rebirth and death frequently underscore the more explicit themes in the novel. The most explicitly mentioned theme that connects to these two is immortality. Kaoru's body, literally the MHC or Ring virus, represents on a more symbolic level, the immortality of the human spirit. Kaoru's character also embodies the typical heroic character who chooses to give up everything in order to save the world.