Onikakushi-hen

Onikakushi-hen (鬼隠し編) is the first arc in the series. It is told from the perspective of Keiichi Maebara, who grows increasingly paranoid and eventually violent as he believes more and more deeply that his friends are trying to kill him.

Plot
Onikakushi-hen introduces Keiichi Maebara, a student who recently transferred to Hinamizawa due to his parents' business. The chapter focuses heavily on the light-hearted school days Keiichi spends with his friends and fellow club members Rena Ryuuga, Mion Sonozaki, Rika Furude, and Satoko Houjou. However, a photographer, Tomitake Jirou, tells Keiichi of a series of gruesome murders that occurred yearly in Hinamizawa. Keiichi attempts to learn more about the incidents from his friends, but they consistently deny that the incidents ever took place which causes Keiichi to grow suspicious of them.

Keiichi attempts to put the past of Hinamizawa behind him but it comes up again when, on the day of the Watanagashi Festival, Tomitake's friend Takano Miyo tells Keiichi about the legend of Oyashiro-sama's curse. The next day, Keiichi learns from a detective, Ooishi Kuraudo, that Tomitake died the previous night under strange circumstances. Keiichi begrudgingly cooperates with the detective in order to discover the truth.

Over the course of the investigation, Keiichi meets clandestinely with Ooishi several times and grows increasingly suspicious of his friends as he learns that they all have connections to victims of the yearly murders. One day, Keiichi skips school under the guise of illness and is visited by Rena and Mion. The pair give him a get-well gift in the form of ohagi. However, the two seem to suddenly change and reveal to Keiichi that they know of his meetings with Ooishi. After they leave, Keiichi tries to eat some of the ohagi but learns that a sewing needle was placed inside one.

The following day, Keiichi arrives at school early in search of a self-defense weapon and ends up taking a metal bat from an unlabeled locker in his classroom, later revealed to belong to a Satoshi Houjou. Keiichi carries the bat constantly and practices swinging it as a ruse to throw off suspicion. Rena and Mion eventually confess to Keiichi that his actions strongly resemble those taken by Satoshi himself immediately preceding his "transfer" out of Hinamizawa. Keiichi's fears turn into insanity as he finds him self increasingly under attack from several villagers, including his friends. After Rena shows murderous intent towards Keiichi, he runs towards the Hinamizawa dam and collapses during a struggle with two unidentified villagers.

After waking from his unconsciousness, Keiichi finds himself in his own room, in the care of Rena. Confused, Keiichi goes downstairs in an attempt to call Ooishi but is greeted by Mion, who ushers him back upstairs. Rena and Mion speak cryptically of having called "the manager" to Keiichi's house and eventually attempt to kill Keiichi using a drug that induces the same circumstances that surrounded Tomitake's death. Keiichi manages to escape their trap and ends up beating the pair to death with Satoshi's bat. Paranoid, Keiichi spots a group of villagers outside of his house and attempts to flee. He eventually finds a telephone booth and uses it to call Ooishi. During the call, Keiichi claws out his own throat, just like Tomitake, and dies a day later in the nearby hospital.

Villagers

 * Keiichi Maebara
 * Rena Ryuuga
 * Mion Sonozaki
 * Rika Furude
 * Satoko Houjou

Outsiders

 * Tomitake Jirou
 * Takano Miyo
 * Ooishi Kuraudo

Mentioned

 * Satoshi Houjou
 * Oyashiro-sama
 * "The manager"

Deaths and Disappearances
All deaths and disappearances are listed only as they are told in Onikakushi-hen and apply only for the individual arc, not the overall series.

Deaths

 * Tomitake Jirou, died of blood loss after clawing out his own throat June 19, 1983 on the night of the Watanagashi.
 * Rena Ryuuga, beaten to death by Keiichi on June 25, 1983 in the Maebara house with Satoshi's old baseball bat.
 * Mion Sonozaki, beaten to death by Keiichi on June 25, 1983 in the Maebara house with Satoshi's old baseball bat.
 * Keiichi Maebara, died from blood loss on June 26, 1983 at the Irie Clinic after he clawed out his own throat in a telephone booth the night before.

Disappearances

 * Satoshi Houjou, disappeared June 1982, one year before the story.
 * Takano Miyo, disappeared on the night of the Watanagashi Festival on June 19, 1983.