Ep. 17: Chapter Four of Festival Music details a strategic plan involving Rika's sacrifice.
Aired on October 30, 2007

17
To save Satoko from terminal Hinamizawa Syndrome infection, Rika volunteers as a test subject for research conducted by Irie and Takano. This development provides further insight into the deaths of Satoko and Rika's parents. The narrative also explores the connection between these fatalities and the legend of Oyashiro-sama's curse, deepening the mystery surrounding the family's tragic history.
Episodes
- Ep. 13 · The eighth and final chapter of the Massacre arc concludes with Rika's tragic sacrifice.
- Ep. 14 · Takano's Disjointed Flashbacks Reveal Harsh Childhood and Hinamizawa Syndrome Research
- Ep. 15 · Takano's Past and Heated Shrine Confrontation with Hanyuu
- Ep. 16 · Festival Music Chapter Three: The Beginning of the End
- Ep. 17 · Chapter Four of Festival Music details a strategic plan involving Rika's sacrifice.
- Ep. 18 · Festival Music Chapter Five reveals Satoshi's past and disappearance reasons
- Ep. 19 · Hanyuu Reveals Her Past as a God to Rika in Hinamizawa
- Ep. 20 · Chapter Seven of Festival Music details Rika gathering allies and investigating enemy supporters.
- Ep. 21 · Chapter Eight of Festival Music details the forty-eight hour timeline