Saiken (True-Clown-Prince)

Saiken (犀犬, Saiken), more commonly known as the Six-Tails (六尾, Rokubi), is a tailed beast once sealed within of Kirigakure. It was later captured by in the anime, then extracted and sealed by Akatsuki. It was later returned to Kirigakure after the, it currnetly resides in.

Background
Saiken first came into being in the waning days of the Sage of the Six Paths' life; to prevent the Ten-Tails' resurgence, the Sage split up its chakra and used his Creation of All Things (万物創造, Banbutsu Sōzō) ability to create nine separate constructs of living chakra, which would become known as the tailed beasts.

Some time after being created, the Sage sat down with all the young tailed beasts and told them that they would always be together even when separated, and that one day they would become one entity again with different names as well as forms than they did then when the time came for them to understand what true power was. Saiken eventually fell into the possession of Kirigakure and was sealed into Utakata.

Appearance
Saiken resembles a large, white, bipedal slug with stubby arms and feet. It has two prominent optical tentacles (eyes) and hole-like openings as a mouth. Its entire body is covered in a slimy substance. During the last remaining days of the Sage of the Six Paths, Saiken was much smaller but still larger than most humans.