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.

Appearance
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.

Personality
The reason he stayed in Hueco Mundo so long was to avenge the deaths of his friends and protect the Human World. He met Rukia and saved her on several occasions. He would have left with her, too, if he wasnt forced to save them from the Menos.

History
Centuries ago, hundreds of hollows infested the Soul Society. Ashido and his friends scared them enough for them to open a Garganta. They followed them back to Hueco Mundo, where they were confronted by the hollows. Soon, all his friends lives would be lost in the battles and eaten by the hollows. Just before his last friends died, he managed to cut the mask off a hollow. Ashido took this mask and uses it to deflect cero attacks. After that, he stayed in Hueco Mundo to decrease the number of Hollows in the real world.

Synopsis
Ashido met Rukia Kuchiki after he rescues her from several menos class Hollows. He proceeds to take her to his hideout, after capturing her forcibly. She realizes he is a Shinigami after seeing his Kido skills and zanpakuto. He attacks her after telling Rukia his name, attempting to test her strength. At the end of the battle he says her skills are good enough to battle Adjuchas.

He agrees to help Rukia find her friends, which leads Rukia to ask him about the mask he wears. He takes it off and tells her his mission to reduce the damage done by hollows in the real world. Sadly, she tells him the number hasn't decreased at all. She also asks why he took her to his hideout, and he replies by saying he wanted his friends to hear a Shinigami's voice. Afterwards, they are confronted by an Adjuchas he has battled numerous times before.

In the midst of battle, the hollow attacks Rukia and she responds by using her second dance, Hakuren, which freezes him a block of ice. Ashido shatters the ice and they return to their search. They meet up with Ichigo and the others and Ashido leads them to the way out. However, several Gillian and Adjuchas appear and attempt to stop them. Ashido takes over the battle and the exit caves in. His current fate is unknown, but Rukia swore to came back for him.

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.