Episode 18: Clothes that Embrace the Mountain
Episode 19: The String of Heaven
Episode 20: A Sea of Brushes
Big Mushishi dump! Watch Episode 17 to find out how the Mushishi get their mail. XD I find the story in Episode 19 to be adorable; there's a certain scene that always puts tears in my eyes. Also, Episode 20 is a bit special in that it introduces another recurring character (she shows up in a later chapter of the manga) and the first Mushi that can actually be described as "evil."