Ūhei

is a ninken and a personal summon of Kakashi Hatake.

Background
In the anime, after they made a contract with Kakashi, Ūhei and the other ninken aided him to search the abducted Rin Nohara by the Kirigakure shinobi and acted as a diversion in order to allow them to flee. They also helped searching for the fleeing Orochimaru.

Appearance
Ūhei greatly resembles a greyhound. He is auburn in colour with a white underside and snout. Along with the standard blue vest with the heno-heno-moheji seal, and a Konoha forehead protector around his neck. He also wears bandages around his neck, head and left, front paw.

Abilities
Ūhei possesses heightened senses which he can use to track his target with ease. He has also demonstrated the ability to track his target underground through the use of the Summoning: Earth Release: Tracking Fang Technique as well as hold a target down, allowing Kakashi to attack them freely. He also has exceptional teamwork with the rest of his pack, able to develop and effectively use several offensive and defensive formations in battle which make use of the manoeuvrability and powerful limbs.

Prologue — Land of Waves
Kakashi called on Ūhei and the ninken 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 Recovery Mission
Later, Ūhei and his fellow ninken were summoned by Kakashi to track down Naruto Uzumaki and his team who had gone off in pursuit of Sasuke Uchiha.

Sunagakure Support Mission
In the anime, he along with the other ninken were summoned by Kakashi to investigate the Takumi Village.

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

Itachi Pursuit Mission
Some weeks later, Kakashi summoned the pack to help track down Itachi Uchiha. He and Urushi were partnered with Sai and he gives Ūhei the name, Pochi as a pet name while tracking Itachi.

Five Kage Summit
In the anime, Ūhei was seen along with Akino, Shiba, Bisuke and Urushi being deployed by Kakashi each carrying scrolls with intel for the other hidden villages.

Kakashi Hiden: Lightning in the Icy Sky
Kakashi summons Ūhei and the other ninken to search for the exploding tags planted around the Tobishachimaru. Once they gather all the tags, the ninken give them to Might Guy.

Trivia

 * In his initial début, Ūhei's ears and tail were shaded a darker colour than the rest of his fur. This was changed in later representations of him.
 * In his anime début and again in Shippūden, Ūhei was initially coloured brown. This was corrected after a coloured manga image was released with him in it, giving him a red and white fur colour.