Ūhei

is a ninken, and personal summon of Kakashi Hatake.

Appearance
Ūhei is brown with a white underside and snout. Along with the standard blue vest with a heno-hen-moheji seal and a Konoha forehead protector around his neck he also sports bandages around his neck and head.

Land of Waves Arc
Kakashi called on Ūhei and the nin-dog pack to track and capture the missing-nin Zabuza Momochi. They managed to bite onto the missing-nin and pin him in place. This allowed Kakashi to use Lightning Cutter without fear of a counter attack.

Sasuke Retrieval Arc
Later, Ūhei and his fellow nin-dogs were summoned by Kakashi to track down Naruto Uzumaki and his team who had gone off in pursuit of Sasuke Uchiha.

Ultimate Weapon Arc
He along with the other ninkens were summoned by Kakashi to investigate the Takumi Village.

Kazekage Rescue Arc
At the start of Part II, Ūhei and the nin-dog pack were called upon to track down the Akatsuki member Sasori using a small piece of his clothing.

Itachi Pursuit Arc
Some weeks later, Kakashi summoned the pack to help track down Itachi Uchiha. He and Urushi were partnered with Sai.