Zero-Tails

The is a creature that identifies itself as a Tailed Beast in Naruto Shippūden 2: Bonds. It has a leech-like appearance and a mask with a giant mouth. It feeds on the darkness in ones heart to create Dark Chakra. It was sealed within Amaru so it could discretely obtain Dark Chakra from the people of Amaru's village. After its task was down, Shinnou used the dark chakra to transform into an "Ultimate Body".