|Original Air Date(s)||August 2, 2007|
|Number of Episodes||1|
Higurashi no Naku Koro ni Gaiden: Nekogoroshi-hen (ひぐらしのなく頃に外伝 猫殺し編, When the Cicadas Cry Side Story: the Cat Killing Chapter) is a one episode special that is set in between the first and second seasons of the anime.
After losing a bet, Keiichi, Mion, Rena, Satoko and Rika parade around the town in costumes. When they come to fork in the road they decide to go to Yagouchi, a nearby village which was abandoned. Once there, Keiichi learns the mystery of the strange haunted quarry from Mion and Rika as they debate whether or not to check it out. It is later revealed in Matsuribayashi-hen that the haunted quarry is being used by Yamainu to store the poison that will be used in the Great Hinamizawa Disaster in case Rika dies.This is probably what happened with the boy in Mion's story: Before they have been chased by the man (Probably one of the members of Yamainu, since the clothes are similar), the boy probably went too far and inhaled the poisonous gas, thus resulting him to faint or die. When the father found his son, he probably also discovered about what "really" happened there, which is the reason why they died. Yamainu, not wanting to be discovered, most likely killed them. Rika knew the truth behind the story, and managed to keep her friends not to go there and be killed before the Watanagashi Festival. The 'Hole' is probably a secret passageway for Yamainu members to enter and exit their hide-out.