The Mystery of Prayer Mountain (Japanese: 祈り山の怪奇,Inori-yama no Kaiki) is the 13th episode of the Yo-kai Watch Shadowside anime. It was broadcasted in Japan on June 29, 2018.
Touma is feeling down, believing it to be his own fault that Shuten Dōji stole something very important from him. However, there seems to be one way to reclaim it: Obtaining a new Yōseiken, the Suzaku Sōtenzan, and fighting Shuten Dōji with it. For that, a contract must be made with the Kenbumajin Suzaku. To reach Kurane Valley in the Yōmakai, where Suzaku is said to be, Touma and the others head for Prayer Mountain in the Human World, which leads there.But, at Prayer Mountain, an eerie Yo-kai hangs in the air, making it feel like even now something bad might show up and something strange is happening to Akinori. Can Touma and the others overcome the trial of fear that awaits them at Prayer Mountain, and make a contract with Suzaku?