The Tailed Beast Kokuō

Kokuō (穆王, Kokuō), more commonly known as the Five-Tails (五尾, Gobi), is one of the nine tailed beasts. It was last sealed within Han from Iwagakure.

Kokuō seems to be a quiet and reserved individual. Though it does not speak much, Kokuō uses the rather old-fashioned "watakushi" (私) when referring to itself, causing it to come across as very polite. It also has pride as a tailed beast, being dismayed at being controlled and being used as Tobi's puppet during the Fourth Shinobi World War. After the end of the war, Kokuō declared that it wants to seclude itself in the forest, which implies it is a pacifistic individual, not wanting confrontations anymore.

Kokuō primarily resembles a white horse, but with a dolphin's head. It has two pointed long horns and three (two in the anime) shorter horns in front.
The ends of its horns, hooves, and tails are tan, with some of the same-coloured spots before the tan areas of its horns and hooves. It also has red markings under its dark blue-green eyes. During the last remaining days of the Sage of Six Paths, Kokuō was much smaller than it is now and its horns were also shorter.

As a tailed beast, Kokuō possesses a massive amount of chakra and can use it to create a Tailed Beast Ball. Its willpower was incredibly strong, as it was the only tailed beast who broke free, albeit briefly, of Tobi's control and attempted to attack the masked man. Kokuō also possesses great physical strength and uses its horns in combat, showing enough ramming-force to injure and knock Gyūki a considerable distance away.