Yagura Karatachi

Little is known about this Jinchūriki yet. He hailed from Kirigakure and on the Chapter 420 cover, seemed to be the host of the Three-Tailed Beast. However, when Deidara and Tobi fought the Three-Tails, Deidara claimed the beast was weak because it had no host. This might possibly be because this Jinchūriki died.

Speculation
It is suggested that he is a relative of Yukimaru, as they both have similar appearances. Also, it's been said that Yukimaru can control the three-tailed beast. It's also likely that he may appear in the current three-tails filler arc. It was also speculated that, judging from the sword on his back, that the Jinchūriki is Mangetsu Hozuki, and that he died when the beast was extracted.