Yamato is the Jinchuriki of the Nibi (Two Tails) which is a nekomata. Some Japanese folk tales said that nekomata could shapeshift, which could mean that the cat that showed up at Sai's place was Yamato. It was believed that after a cat reached ten years of age, its tail would slowly split into two tails, and along the way would develop magic powers, primarily those of necromancy and shamanism. By gesturing with its tails or with its forepaws, nekomata were said to animate and control the dead. Nekomata in the wild were also said to feed on the corpses as carrion, as well. Resembels Zetsu's body don't you think? This could mean that Zetsu is the Akatsuki member that would get the Nibi. These will probably lead to a confrontation between them at the heaven and earth brigde, which lies in Kusagakure (Hidden Grass), Zetsu's former village. Zetzu's ring has the kanji 玄 (Gen, mysteriousness).