Bisuke

is a ninken and a summoning of Kakashi Hatake. He bears an uncanny resemblance to Gaara with a kanji imprinted on his head and dark rings around his eyes. However, where Gaara has the kanji for, Biscuit has the kanji for.

Part I
Kakashi called on Biscuit and the nin-dog pack to track and capture Zabuza Momochi. They managed to bite onto the missing-nin and pin him in place. This allowed Kakashi to use Lightning Blade without fear of a counter attack. A short time later, Biscuit and his fellow nin-dogs would be called upon by Kakashi to track down Naruto Uzumaki and his team who had gone off in pursuit of Sasuke Uchiha.

Part II
Several years later, Bull and the nin-dog pack were called upon to track down the Akatsuki member Sasori using a small piece of his clothing. Later in the anime, he is summoned by himself (since Pakkun was busy) to find Naruto, who had gone after Yuukimaru. During the hunt for Itachi Uchiha, Biscuit was partnered with Sakura Haruno.

Trivia
Bisuke means Biscuit, referring to dog biscuits.