Isobu (True-Clown-Prince)

Isobu (磯撫, Isobu), more commonly known as the Three-Tails (三尾, Sanbi)

Background
Isobu 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.

At some point in the past, Isobu fell into the possession of Kirigakure and was sealed within Yagura, the Fourth Mizukage. However when Akatsuki went after it the beast was in the wild; the story behind how it came to be like this is still unknown. It was also stated by Tsunade in the anime that Isobu disappeared after a great war.

Appearance
Isobu primarily resembles a large turtle, but with a crab-like shell, and three shrimp-like tails. Under its shell, it has red, muscle-like tissue. It has a pair of human-like arms and hands, but no hind-legs. Its lower jaw is rather big and has teeth-like horns, together with its big forehead, which also has horns, it somewhat resembles a mouth with big teeth, making it look like the rest of the face is inside the mouth. Its eyes are dark and have red pupils. In the anime, the eyes are red with green pupils. Its right eye is constantly closed, indicating some sort of injury, and because of this, it is particularly vulnerable to attacks directed at its right eye. During the last remaining days of the Sage of the Six Paths, Isobu was much smaller than it currently is but was still many times larger than the Sage.