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. We can't be sure whether Yūkimaru is male or female, but for now we consider him male, as Kabuto used the suffisix '-kun' for him which is rarely used for girls and mostly for boys.

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.