Kamatari

is a giant, apparently one-eyed weasel holding a sickle with which it can cause a lot of destruction in a short amount of time. Its sickle is almost as large as itself. After it starts moving, it can't be seen by the unaided human eye.

Abilities
It is summoned using Temari's Giant Folding Fan as a medium through the Summoning: Quick Beheading Dance, after which it slices down all in its path with enough force to decimate an entire forest.

Part I
Kamatari has only been seen twice in the series and only for a few seconds after its summoning, once in the Sasuke Retrieval Arc, and once in the final filler arc.

Trivia

 * Kamatari is an obvious reference to the Japanese yōkai ; however, instead of being simply a weasel with razor sharp-claws, it is literally a with a.