What Lives in the Lake (The Anime)

S1 E13: This is an anime-original episode. When the Impala breaks down in Louisiana the boys learn the town has been suffering from a series of demonic omens and accidents. But in each incident, no one is actually hurt or maimed. Sam concludes that the creature is a harmless, friendly creature that lives in the lake, sometimes referred to as "Kappa" in Japan; It helps humans in return for taking a little bit of a food from them. In the end it turns out that it all was much ado about nothing and had nothing to do with demon. Even Sam and Dean sometimes make mistakes...