Name: Kunashi
Look: The bijuu itself is quite massive, actually the largest bijuu in terms of pure mass, as well as energy, chakra and power. Well, it IS the eight-tails, isn't it. It is the only known Bijuu to be able to match the power of the Nine-tails, and with the The snake itself is connected by one gigantic, samurai armor-covered torso which has connected to it eight heads protected by odd, demonic helmet's that resemble japanese shogun armor. It's eyes as well as it's scales glow a bright, deep red and each tail is tipped with some ort of thick weapon. [An axe on the first, club on the second, halberd-head on the third, broadsword on the fourth, mace on the fifth, a spear-head on the sixth, a morningstar which can be fired off to do truly massive damage on the seventh, and a saw on the eighth] Each head also has a small [by their standards, at least] spear-like spike upon their head.
Appearance: At the start of his transformation, Kisai's eyes will become red and snake-like, and begin to glow. His skin begins to deepen into a pale, snake-like white color for the time-being and a deep, purple chakra surrounds him. So far, this is the only stage that has been spotted. A tail, snake-like and very long, made of pure chakra will be seen slowly extending before wrapping the boys body.
Element: The 8-tailed snake has the ability to control steam, toxic, soul, dark and storm releases. Therefor, he can use Lightning, Water, Katon and Earth chakra nature's.
Description: With the bijuu's power the jinchuuriki possesses chakra beyond that of the rest of the bijuu combined[yes, even Kyuubi, remember that the 8-tails RELESED the rest of the bijuu, thus giving them powuh!], allows the boy to move very fast [about the speed of a swift Kage], attack about 40X the strength of a usual jounin and can use jutsu with fewer handseals. These stats seem to advance with each tail. He also controls the true wielder of the Kusanagi no Tsurugi, and can unlock it's true power when it's Jinchuuriki wields the sword.
History: Each head of Yamata no Orochi represents a symbol: Soul, Ghost, Evil, Devil, Monstrous, Kill, The Afterworld and Death. Its powers were originally weak, the members of the Kusanagi clan, when attacking it, acted carelessly, using the legendary sword Kusanagi no Tsurugi . Because of that, as a consequence, Yamata no Orochi takes the sword from them, absorbing the power contained inside, and becoming an incredibly powerful creature, and finally storing it in its body. With the new power, Yamata no Orochi releases an insane amount of dark energy, awakening the other Bijuu and becoming arrogant.