Watanagashi-hen

Watanagashi-hen (綿流し編) is the second arc in the series. It is told from the perspective of Keiichi Maebara and follows a string of bizarre murders in Hinamizawa that occur following the Watanagashi Festival.

Plot
During one of the club's activities, the group all visit a toy store and the owner ends up giving every member except for Mion Sonozaki a doll. Keiichi Maebara finds his doll to be too girly and decides to give it to Rena Ryuuguu, figuring that Mion wouldn't want it since she's apparently more into guy-ish things. Keiichi visits the restaurant Angel Mort with his father and finds a girl named Shion working there. Shion tells Keiichi that she is Mion's twin sister, however Keiichi believes Mion is simply putting on a more girlish facade in order to live out a different personality. Despite Shion consistently telling Keiichi that she isn't Mion, Keiichi refuses to believe her and eventually goes out with Shion several times, believing her to be Mion.

As things in the club become increasingly awkward, Rena tells Keiichi that he has hurt Mion deeply in some way. Meanwhile, Rika Furude begins skipping club meetings in order to train as a shrine maiden for the upcoming Watanagashi Festival.

One day, Keiichi and Shion visit the toy shop where Keiichi originally received the doll and Shion asks him to buy the same doll for her. In the shop, Keiichi is shocked to find Mion working there. Shion explains once again that she is Mion's twin sister, laughing at the whole affair. Following this incident, Mion and Keiichi stop speaking to each other for a period of time.

At the Watanagashi Festival, the club meets up with Jirou Tomitake, Miyo Takano and Shion. Shion and Miyo tell Keiichi about the gruesome past of the Watanagashi Festival, much to Keiichi and Mion's dismay. During Rika's performance at the Festival, Shion pulls Keiichi aside to spy on Jirou and Miyo, who seem to be fiddling with the lock on a storage shed behind the temple. Shion and Keiichi eventually join Jirou and Miyo when they enter the storage shed and discover an array of old torture implements inside. While inside, Tomitake and Shion hear an increasingly loud noise reminiscent of a girl jumping on a wooden floor, though Keiichi and Miyo appear unable to hear the noise.

Soon after leaving the shed and parting with Keiichi and Shion, Jirou and Miyo are found dead, seemingly killed under strange circumstances. Since the pattern for the Watangashi Festival thus far has been that one person dies and one person disappears, Keiichi and Shion come to the conclusion that the death of both Jirou and Miyo means that Keiichi and Shion are destined to disappear.

However, more and more people in the village go missing but Shion and Keiichi and strangely unharmed. Shion confides nightly with Keiichi over the phone about her worries regarding the disappearances. After Satoko Houjou and Rika disappear, Mion begins to act strangely around Keiichi. Keiichi later learns from Detective Ooishi Kurado that Shion disappeared the night after the Festival and figures that the Shion he had been speaking to on the phone was, in fact, Mion.

Keiichi and Rena work out that Mion is the clear suspect in all the deaths and disappearances so far and, along with the police, confront Mion with their findings at the Sonozaki residence. During their conversation, Mion reveals the dark history of Hinamizawa and the Sonozaki family and confesses to all the murders and disappearances that have occurred. Before turning herself in, Mion requests that she have 30 minutes alone with Keiichi. However, Mion tricks Keiichi into following her into the Sonozaki torture chamber and reveals that Shion is still alive. Mion incapacitates Keiichi with the intention of torturing him in front of Shion. Rena, seeing through Mion's deception, called the police to enter the Sonozaki residence which cuts Mion's plans short. Mion escapes through an undiscovered escape route deep within the torture chamber and Keiichi and Shion are rescued.

Shion is heavily traumatized and, after a medical stay, begins to sleep in a different house each night due to her fear that Mion will return for her. Keiichi's family receives over $200,000 from the Sonozaki yakuza as a form of compensation and hush money and are eventually given a letter asking the family to leave Hinamizawa. Before the family departs, Keiichi meets Mion one last time outside his house. Keiichi, excited to meet her one last time so that he can give her the doll he should've given her from the beginning, is surprised when Mion stabs him in the stomach with a knife and runs off laughing. Keiichi is taken to a hospital and treated for his wounds where he meets Ooishi once again. Shion is revealed to have fallen to her death at her apartment, which Keiichi believes was an act of murder. Ooishi gives Keiichi a bit of information about the case so far as closure and departs. Keiichi then hallucinates an un-dead Mion attempting to torture him and dies in his hospital bed.

Villagers

 * Keiichi Maebara
 * Mion Sonozaki
 * Shion Sonozaki
 * Rena Ryuuguu
 * Satoko Houjou
 * Rika Furude

Outsiders

 * Ooishi Kuraudo
 * Jirou Tomitake
 * Miyo Takano

Mentioned

 * Oyashiro-sama
 * Satoshi Houjou
 * Oryou Sonozaki
 * Kiichirou Kimiyoshi

Deaths and Disappearances
All deaths and disappearances are listed only as they are told in Watanagashi-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.
 * Takano Miyo, killed and burned in an oil drum in the Gifu Mountains June 19, 1983 on the night of the Watanagashi. Upon investigation, the corpse is revealed to have been dead for over 24 hours at the time of discovery, which conflicts with Takano's reported appearance during the Watanagashi Festival.
 * Kiichirou Kimiyoshi, killed in the Sonozaki torture chamber. His body was found in a well on June 23, 1983.
 * Rika Furude, killed in the Sonozaki torture chamber. Her body was found in a well on June 23, 1983.
 * Oryou Sonozaki, thought to be ill in her home. Her corpse was found in a well on June 23, 1983.
 * Shion Sonozaki, became mentally ill after being rescued by police on June 23, 1983. Fell from her apartment in Shishibone and broke her neck on June 28, 1983.
 * Mion Sonozaki, fell into a well and broke her neck on June 23, 1983.
 * Keiichi Maebara, stabbed in the stomach on June 28, 1983. Died in a university hospital a few days later following a hallucination.

Disappearances

 * Satoshi Houjou, disappeared June 1982, one year before the story.