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.

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.

Keiichi comes to the resolution that he must kill Teppei. After brutally beating him to death with Satoshi's baseball bat, he buries the body, and on his way back home, Keiichi bumps into a suspiciously acting Takano.

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.

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

Keiichi tries to dissuade Rena, but is confronted by her with his own dark secrets. After confessing his past sin to his friends, he finds that he can recall events from Onikakushi-hen, even though they have no bearing on the current situation.

Rena's madness reaches the peak to the point of taking all the school children hostage. With the police's help and working together with the rest of the group, Keiichi manages to defuse a homemade bomb Rena planted on the rooftop of the school. There, the two have a final confrontation and even though he is defeated, Keiichi manages to get Rena to realize she should have trusted and confided in her friends.