Episode 11: Curse of the Man-Eating Pond
Summary:
When Moroha chokes on pancakes, she races to get water and very nearly makes a deadly mistake. The source of water turns out to be a human-eating swamp! Thankfully, Towa stops her in time.
Later that day, Towa and Setsuna are told by Kohaku and the demon slayers about the swamp and how it use to be a beautiful pond. He sends them to investigate and destroy whatever it is that has been eating people, beasts, and birds.
As they are approaching the murky pond, Setsuna notices a brother and sister fighting. The boy wants to avenge his parents, who were eaten by the pond. His sister, Chiyo, falls trying to stop him. Towa and Setsuna take the kids home and bandage Chiyo's knee. The kids tell them of a giant Venom Serpent that is living in the pond. As the sun is setting, the girls are invited to stay the night.
That evening, the children ask Setsuna to play her violin. As she does, they begin to cry. Their father use to play the Biwa (a similar instrument) for them by the pond, but he was swallowed up by the serpent.
The next day the girls are joined by Moroha. They discover that they are not only fighting the Venom Serpent, but the pond itself which is a water-demon called Drifting Pond.
In their fight to clear the pond, all the girls are affected by the demon venom in one way or another. However, Towa manages to destroy the Venom Serpent, while Setsuna uses a patch of medicinal herbs to purify Drifting Pond.
The pond, once again, has clear, glistening water.