Ten-Tails

Across its many incarnations the creature keeps a titanic, brown-toned body, a single vast eye, the Rinne Sharingan, filling most of its head, and conch-like spikes rising along its back. Dragged back incomplete by Madara and Obito, it first appeared as a bulbous, plant-veined mass with long clawed arms, no rear legs, a wide fang-filled mouth, and a lone chin spike, its tails capped by furled buds.

Growth reshaped it repeatedly. It thinned into a gaunt humanoid whose eye stayed forward while a single ear formed and its grinning mouth slid to one side amid a crown of horns, the tail-buds splitting open to bare human hands. Further stages fleshed it out, regrew its missing arm, and set it upright on two legs with a heavier, muscled frame; by the era of Hagoromo and Hamura it towered above mountain ranges, bloated and studded with extra spikes.

Two other shapes appear. Obito later cast out a construct that unfolded into a giant tree topped by a purple bud that sheltered the eye, dwarfing every prior version. And when the chakra within Kaguya slipped free, she twisted into a pale, swollen, rabbit-like Ten-Tails, the nine beasts' heads budding across its body while her forehead Rinne Sharingan and ten hand-tipped tails remained.

Long before the hidden villages, in an age of unending war, the Ōtsutsuki planted a God Tree designed to drain the planet's chakra and blossom once every thousand years. Princess Kaguya defied the ban on eating its fruit, seized tremendous power, and ended the fighting. After she bore the first two children able to wield chakra, she reclaimed their power by fusing with the tree and became the rampaging beast, though bystanders assumed the tree itself had turned monstrous to take back what she had taken.

Her sons Hagoromo and Hamura at last sealed the creature, hurling its body into the moon while Hagoromo took its chakra inside himself as the first jinchūriki, earning lasting renown under the name Sage of Six Paths. Aware his death would free it, he parcelled its power out among nine tailed beasts. Kaguya, meanwhile, had already made Black Zetsu to arrange her comeback, and across the centuries it guided bloodlines until the Rinnegan awoke in Madara Uchiha, who called the hollow husk back and christened it the Outer Path's Demonic Statue.

Madara, and Obito following him, laboured to fold the nine beasts back into the statue so the full creature could fuel their Eye of the Moon Plan. Empty of any wish or feeling, it cannot be traced through negative emotions and serves instead as the instrument of Kaguya's hidden will. It rose again and again through the Fourth Shinobi World War, hosted in turn by Obito and Madara, until Kaguya's own revival and later sealing folded it once more into the statue.

Hailed as the fountainhead of all that exists, the Ten-Tails carries reserves so immense that Kurama reckoned one lone tailed beast could never stand against it, and Naruto's Sage Mode could not even take its measure. It drinks up oceans, splits the earth, lifts mountains, and gives off the very signature of the world's natural energy, so ordinary sensing cannot find it even as it bends that energy to its will. Gyūki warned that letting it reach its ultimate form would leave it unbeatable.

Its size masks alarming quickness and might; it caught Naruto and Killer B faster than either could react, swatted a Tailed Beast Ball aside with one finger, and tore up the landscape with a single sweep of a tail. Point-blank Tailed Beast Ball blasts and wind-driven black flames barely troubled it. Being the original beast, it forms its own Tailed Beast Ball, loosed first as an unbroken beam and later as a cone able to level whole cities, and it can spread a flower-shaped cannon for still greater shots. Its bellow rouses continent-wide catastrophes called Tenpenchii.

The beast remakes its own flesh to regrow limbs, slough off burning tissue, and sprout new hands, and it buds off agile fission beings to defend itself. In tree form its roots stretch out, siphoning chakra and withering victims within seconds, and once the crowning bud opens, the eye it hides can switch on the Infinite Tsukuyomi, wrapping the world's people in cocoons that slowly grind them into White Zetsu. A Rinnegan wielder who performs the Ten-Tails Coffin Seal, a technique of the Six Paths, can make himself its host, coming away with ten Truth-Seeking Balls and Six Paths Senjutsu itself; a will too frail to tame it, though, may be swallowed by the beast instead.