S1·E6 Watadamashi-hen: Cotton-Deceiving Chapter, Part 2

Keiichi learns about the yearly murders from Shion, Miyo, and Jiro. At the festival, Shion drags Keiichi away from Rika's dance and the two run into Miyo and Jiro, who are breaking into the ritual tool shed. They decide to go inside to look at it with Miyo.