Yagura

Yagura (やぐら) was the jinchuriki of the Three-tailed giant turtle and the Fourth Mizukage (四代目水影, Yondaime Mizukage) of Kirigakure. When the Three-Tails was captured by Akatsuki, it had no host and roamed out in the wild. The reason why the Three-Tails was removed from Yagura is unknown.

History
Yagura and the Three-Tails.During his time as Mizukage, until the massacre of Acadamy students by a young Zabuza momochi, the village was known as the "Village of the Bloody Mist" (血霧の里, Chigiri no Sato), due mostly because of the barbaric ritual where Academy students kill one another for graduation. It is likely that Yagura was the Mizukage whom Zabuza tried to assassinate.

Despite the terror of his reign, Yagura appeared to be kind. Apparently the people of Kirigakure feared that Yagura was being manipulated, a fear which was confirmed by Ao, who saw through an unnamed genjutsu with his Byakugan

Eventually, the Three-Tails was removed from Yagura for unknown reasons, and the beast was allowed to roam free. With that, Yagura's life and reign came to an end.

Abilities
Yagura was presumed to be a powerful shinobi due to him being chosen as the Mizukage and was one of the few jinchūriki that were able to fully control their tailed beast. He wielded what seems to be a large staff, with two hooks on each end, one larger than the other, along with a flower on the larger end.

Trivia

 * Because Yukimaru has some control over the Three-Tails, and because he has some resemblance to Yagura, it is speculated that they have some connection to each other; however, Yūkimaru is an anime-only character that does not appear in the manga.
 * Yagura is one of only four people said to be able to truly control a bijuu, the others being Hashirama senju, Madara uchiha, and Killer Bee. He and Killer Bee are the only two Jinchuriki said to be able to fully control their bijuu
 * Yagura is one of three jinchūriki known to have been a Kage, the others being Gaara and Naruto.
 * The word "Yagura" (櫓 or 楼) means "tower" or "turret". It could also refer to the tombs in the middle ages.