Back in June 1983, the club participates in a game of "zombie tag". On their way home, they run into Irie, Tomitake, and Takano, who tell Keiichi about the yearly murders known as "Oyashiro-sama's Curse". However, he understands why his friends hid it from him and doesn't resent them for it. Regardless, this fails to reassure Rika, as she grows progressively depressed as the day of the Watanagashi Festival approaches.

Satoko worries about Rika's depression and tries to confront her about it, but Rika continues to deny anything is wrong. In the middle of the night, Satoko is woken by Rika arguing with a mysterious voice, and telling her she will soon be murdered, and there is nothing that either of them can do.

The day of the Watanagashi Festival comes, and once again Rika fails to warn Tomitake of his imminent death. Later, Satoko is convinced that a mysterious man is following her and Rika around, even though no one else has noticed any such thing. Worried of Rika's safety, she sets traps around the house to alert her of any intruders, and when one is triggered, her fears are confirmed.

Much to Satoko's surprise, Rika hides her before letting her murderers take her away. After witnessing Rika's demise and the death of the remaining villagers, Satoko fights desperately for her life.

The fight to save Satoko from her uncle's abuse continues, but they stumble on a dead end because she is reluctant to denounce him, for her own reasons. Rika realizes that despite their, she is the one who must take action.

After getting a clue of the villain's betrayal, Rika tells her friends the truth behind the Hinamizawa Syndrome, and her connection with it. Meanwhile, the enemy moves on with their plan, eliminating any opposition.

Takano's past is revealed in disjointed flashbacks, some of them showing her harsh childhood, while others to the time when she became involved with researchers of the Hinamizawa Syndrome.

Takano's story continues, including how she met her foster grandfather, and her determination to continue his work. A few years later, Takano and Hanyū have a very heated confrontation at Oyashiro-sama's shrine.

Hanyū watches silently and hopelessly as the cruel events occur during the dam incident, while she and Rika eagerly await the arrival of the one person who will be the key element to bring an end to the enemy's intentions.

Hanyū is physically introduced into the world as a transfer student to the Hinamizawa school, but forgets her role. After a brief meeting with Takano and Tomitake, she remembers the past worlds and informs Rika about the enemy's intentions.

Finding that Tomitake is captured, Irie rushes to escape and ends up meeting with Shion and her bodyguard, Kasai, on their way to the Sonozaki Estate. However, by accepting their help, he ends up unintentionally revealing Rika's hideout to the enemy.

Irie, Kasai, and Shion head to the clinic to rescue Tomitake. Irie finally unveils to Shion where Satoshi disappeared to and the others deal with the enemy assaulting the mountains on their location

Keiichi Maebara, a student who recently moved into the village of Hinamizawa, is invited by his new friends at school to join their club. But while searching for treasure at a garbage dump with Rena Ryugu, he discovers the village is not as peaceful as it seems.

Keiichi meets Mion's twin sister, Shion; the two are so identical that Keiichi can hardly tell the difference between them. It is also revealed that Mion has a crush on him.

Keiichi's parents leave for Tokyo for a few days. Helped by Satoko and Rika, who makes dinner for him, Keiichi learns about Satoshi, Satoko's older brother, and his mysterious disappearance on the night of last year's Watanagashi.

Satoko is absent from school for a few days. After discovering that the cause of her absence is Teppei, her abusive uncle, who left Hinamizawa after his wife was murdered on the night of Watanagishi, but recently has returned, Keiichi decides to intervene.

Rena discover the true character of her father's girlfriend and grows a deep hatred for her.

During Rika's ritual performance at the Watanagashi Festival, Shion whisks Keiichi away to sneak into the forbidden shrine warehouse, where Tomitake and his friend, Miyo Takano, are waiting. However, after learning about the other pair's fate, he starts to worry about his and Shion's safety.

Four years ago, during the dam incident, young police investigator Mamoru Akasaka comes to Hinamizawa to find leads to a child kidnapping. After hearing an enigmatic warning from a younger Rika, Mamoru becomes suspicious of some of the townsfolk.

The events from Watanagashi-hen are retold from another point of view. Shion takes Mion's place in Hinamizawa and is lovestruck by Satoko's older brother, Satoshi, at their first meeting together. But after discovering about the trouble he spends to protect Satoko, Shion starts to loathe her.

The annual Watanagashi Festival finally starts, and everyone has fun feasting and playing games. However, in the following day, Keiichi is interrogated by chief police officer, Oishi, about a crime that occurred at the night of the festival, and he starts fearing the villagers might be involved in this and other similar incidents, like Oishi suspects.

Keiichi asks Rika for help, but when she and Satoko disappear, he starts fearing for the worse.

Akasaka and Oishi find the kidnappers' hideout and rescue the boy. After discovering that their efforts were in vain because the perpetrators' demand was already conceded, he realizes the real meaning behind Rika's words to him.

While studying Takano's scrapbooks, Rena starts to unveil the the truth behind Oyashiro-sama and Hinamizawa's dark past.

Keiichi's mentality is shaken when his friends tells him that he was actually at the Watanagashi Festival with them and Satoko still bemoans her uncle's abuse, despite being sure about having him dead. His confusion grows when he tries to unsuccessfully find the truth.