Yūkimaru

Yūkimaru is a young boy (it is still unknown if he is a shinobi) who appears in the second Naruto Shippūden filler arc. Little is known about him yet. He seems to be a test subject of Orochimaru and has androgenous looks. His appereance looks very similar to that of the former Jinchūriki of the Three-Tailed Beast (Sanbi). Since the arc where he appears in does involve the Three-Tailed Beast, it might be possible he is related to the Jinchūriki, or is the Jinchūriki himself.

Hunt for the Three-Tails Arc
So far we have only seen him once in this arc, collecting tree flowers after Sasuke cut them off with his Chidori for his training. He had a teaser appereance in Shippūden episode 87, in a preview for the upcoming arc. In that scene we saw Naruto sitting in an onsen (hot pool) and Yūkimaru nearing him and asking him or two hearts could communicate.