Ashido Kanō

, is introduced during the anime's adaption of the Hueco Mundo arc. He was originally set to appear in the manga during the same part in the series, but had to be cut by series creator Tite Kubo due to time issues.

Character Outline
He wears the standard Shinigami uniform, in ragged condition and without any footwear, with a fur coat draped over himself. The coat consists of several Hollow masks adorned on it; one (resembling a gazelle's skull) killed his best friend. The others he uses to block hollow attacks. He appears to be quite strong as he is able to defeat adjuchas class menos with out releasing his zanpakutō.

History
Hundreds of years before the current Bleach storylstory-line, Ashido along with his fellow Shinigami were fighting with a group of hollows but when the hollows tried to retreat into Hueco Mundo Ashido and the shinigami followed them. However, the Shinigami were instead hunted down by the Hollows and killed one by one, leaving Ashido as the sole survivor.

Though he was to return to Soul Society once he wiped out the Hollows (an impossible task given how many reside in Hueco Mundo), he decided to stay and kill as many hollows as possible, hoping to reduce the numbers appearing in the human world.

Synopsis
Ashido met Rukia Kuchiki after he rescues her from several menos class Hollows, and takes her to his hideout. Once there he proceeds to test her strength, he concludes that she is strong enough to survive, and decides to help her reach her friends. Along the way they stop at the grave of his former teammates, and Ashido tells Rukia that he just wanted them to hear the voice of a Shinigami once again. After reuniting Rukia with the rest of her friends, Ashido tries to join them in leaving the realm, though is trapped in a cave-in while protecting her group from some attacking hollows in a self-sacrificial effort. His current whereabouts and condition are left unknown.

Powers & Abilities
Considering the amount of time he spent in Hueco Mundo and continuously fought Gillian-class and Adjuchas-class Hollows, Ashido is very powerful, able to fight on par with officer-level Shinigami and Adjuchas-class Hollows, even without releasing his zanpakutō.

Mask Shield: In addition to using a zanpakutō in battle, Ashido carries a shield crafted from Hollow masks. The shield has proven to be of great use, for it can withstand and deflect cero blasts from both Gillian-class and Adjuchas-class Hollows.

Expert Swordsmanship Specialist: Ashido has displayed great swordsmanship skills, especially since he is able to fight on par with adjuchas-class Hollows and officer-level shinigami without releasing his zanpakutō.

Flash Steps Expert: After saving Rukia and while searching for Ichigo Kurosaki and his group, he displayed that he could exceptionally use flash steps.

Kidō Practitioner: His skill with kidō is unknown, but Rukia notes that the light he made to light up his hideout was made with kidō.

Zanpakutō
Ashido's zanpakutō has a green hilt and a square tsuba, which is chipped, likely showing that Ashido has been in many fights within the Menos Forest since the time he arrived. Ashido never releases his zanpakutō when he is shown. It is unknown if he even knows shikai.

Trivia

 * With his mask on, his face looks very similar to Allon, the chimera.