Yagura Karatachi

was the jinchūriki of the Three-Tails and the of Kirigakure. When the Three-Tails was captured by Akatsuki, it had no host and roamed out in the wild. However, upon his resurrection, the Three-Tails appears to have been resealed within Yagura.

Background
During his time as Mizukage, the village was known as the, mostly because of the barbaric ritual where Academy students kill one another in order to graduate. This practice was discontinued when an entire graduating batch of Academy students were massacred by a young Zabuza Momochi. It is likely that Yagura was the Mizukage whom Zabuza tried to assassinate when he revolted.

Yagura was also known to dispatch Kiri-nin who were suspected of being disloyal to the village immediately (commending and taking Kisame Hoshigaki as his direct subordinate after assassinating Fuguki Suikazan, a traitorous member of the Seven Ninja Swordsmen of the Mist). Yet despite the terror of his reign, he appeared to be kind. Apparently the people of Kiri feared that Yagura was being manipulated, a fear which was confirmed by Ao, who saw through an unnamed genjutsu with his Byakugan, later identified by Kisame as the work of Tobi.

Appearance
Yagura is a young man with messy light-grey hair (brown in the anime), pink pupiless eyes and what seems to be a stitch-like scar running from under his left eye, all the way down his cheek. He is small in stature and wears a grey, sleeveless shirt with the Kirigakure forehead protector attached to the front, short-sleeved mesh armour over which he also wears a green poncho along with a turquoise sash around his waist, paired with a green apron over his pants. He wears a pair of brown boots, and on his back he carries a staff-like pole weapon with uneven sized hooks with a green flower on the larger end.

Abilities
Not much is known about his abilities except that he was presumed to be a powerful shinobi, due to him being chosen as the Mizukage. He wields what resembles a large, hook-ended staff with one end being larger than the other. A green flower is also located on the larger end. By incorporating this tool into his Water Release ninjutsu, Yagura is able to create mirrors that can reflect enemy attacks.

Jinchūriki Transformations
As the Three-Tails' jinchūriki, Yagura is granted a significant amount of chakra and stamina from the beast. He was also one of the few people mentioned by Danzō Shimura to have achieved full control over their respective beast. On his resurrection he displayed a partial transformation into the Three-Tails, being able to manifest one of its tails. Furthermore, when attacked and immobilised by B's clone, Yagura transformed into his Version 2 form to escape being sealed. In this form Yagura was able to perform Coral Palm, a technique which makes corals to grow on any surface he chooses, when used on opponents, it restricts their movement and eventually immobilises them.

Shinobi World War Arc
In preparation for the Fourth Shinobi World War, Yagura is resurrected by Kabuto Yakushi to fight against the Allied Shinobi Forces, before being mobilised alongside the other deceased jinchūriki.

As dawn breaks on the second day, it is revealed that Tobi had turned the revived jinchūriki into his own customised Six Paths of Pain, with each having a Rinnegan and Sharingan in place of their left and right eyes respectively. Each jinchūriki also had their particular tailed beast resealed within them and a chakra receiver embedded into their body. Yagura is later seen travelling together with Tobi, in pursuit of Naruto and Killer B. Encountering their targets, the revived jinchūriki were sent into battle. After the enemy evades Rōshi's attack, Yagura uses his Water Release: Water Mirror Technique to counter their attacks, repelling them momentarily. However, when this initial assault fails, he, like the others, unleashes the power of his respective tailed beast by materialising the first of its tails.

Incapacitated in the wake of the Eight-Tails' devastating attack, after B's recent transformation, Yagura is then restrained by the latter's sealing technique. However, before the technique's completion, he manages to escape by adopting his Version 2 form, where he then proceeds to strike Naruto from behind using his Coral Palm technique. Regrouping with the other revived jinchūriki, after Kakashi Hatake and Might Guy's intervention, Yagura charges past the pair towards Naruto.

Rallying once again, he along with the other jinchūriki prepare to confront the two Konohagakure jōnin, after Han's previous attack is thwarted by Kakashi.

Trivia

 * The word means "tower" or "turret". It could also refer to the tombs in the middle ages.
 * Technically speaking, Tobi was the true Fourth Mizukage.