Ashido Kanō

, is introduced during the anime's adaptation 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, which he utilizes in a variety of ways. The one resembling a gazelle's skull which he wears over his face is the mask belonging to the Hollow that killed his best friend. Ashido uses the rest to block Hollow attacks, and carries one of them like a shield during battles.

Personality
Ashido is shown to be rather serious most of the time, having carried the mental scars created by the deaths of his teammates for many centuries. The very reason Ashido stayed in Hueco Mundo so long was to avenge the deaths of his friends and protect the human world by killing as many Hollows as he possibly could. He met Rukia and saved her on several occasions, and would have left the forest with her group if he had not been forced to save them from the Menos. Even after several centuries of living alone in Hueco Mundo, Ashido still harbors a sense of sorrow at having lost his companions and visits the site of their death from time to time to pay his respects. He later brings Rukia to this same spot, claiming that it would be nice if his deceased friends could hear the voice of another Shinigami.

History
Centuries before the main Bleach storyline, hundreds of Hollows infested the Soul Society from Hueco Mundo. Ashido and his companions appeared to combat the threat, and eventually drove them to open a Garganta. Believing that it was necessary to destroy the enemy, Ashido's team followed the Hollows back to Hueco Mundo, where the battle waged on until they were eventually overcome by the Menos Grande. Although they fought bravely, one by one his companions were rendered too weak to resist and eventually lost their lives. Just before his last friends died, he managed to cut the mask off a Hollow. Ashido took this mask for himself and used it to deflect the cero fired by the Menos Grande, and somehow managed to survive the onslaught. After that fateful day, he chose to remain in Hueco Mundo and kill as many Hollows as possible in an attempt to decrease the number of Hollows appearing in the real world, believing that it is his duty as a Shinigami.

Hueco Mundo arc
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 Kidō skills and Zanpakutō. 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. Later, they are confronted by an adjuchas and 6 menos, which Ashido dispaches after blocking their joint ceros. Rukia comments she is amazed that he is fighting on that level without even using Bankai, and with just an an unreleased sword. Another adjuchas attacks them shortly after, where Ashido loses his old mask after protecting Rukia. After that, the adjuchas calls her 'dead weight', implying that she was holding Ashido back. Ashido let Rukia kill this Adjuchas with her first dance, Tsukishiro, to prove her strength. Rukia apolagized for getting his mask broken, and points out he should come back to soul soiciety. He gives a non-commital answer saying 'we all choose our own path'. 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 come back for him.

Equipment
Ashido possesses several items crafted from Hollow masks. He uses each of these items for different purposes.

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.

Cloak: Ashido wears a fur cloak with many Hollow masks attached to it. It is unknown if this cloak has any special properties, but it is assumed that Ashido at least uses it to avoid drawing attention from the Hollows that reside within the Forest of Menos.

Mask (Former): Ashido is usually wearing a Hollow mask covering his face. The mask was obtained when Ashido arrived in the Forest of Menos, as one of his teammates died while being ambushed by a Hollow wearing that particular mask. The mask itself is highly durable, as it was initially used as a shield to deflect various Cero blasts from Gillian-class Menos. It also protected Ashido from harm when he saved Rukia Kuchiki from a lethal blow from an Adjuchas-class Hollow. However, the mask was broken as a result.

Powers & Abilities
Expert Swordsmanship Specialist: Ashido has displayed great swordsmanship skills, especially since he is able to fight on par with Adjuchas-class Hollows and outclass officer-level Shinigami without releasing his Zanpakutō.

Shunpo Expert: When he first appeared when Rukia was being fired at with a cero, he managed to use shunpo to appear between Rukia and the blast, grab her, and shunpo out of the way before the cero hit either of them. After saving Rukia and while searching for Ichigo Kurosaki and his group, he displayed that he could exceptionally use Flash Steps. He has also displayed that he could use Flash Steps proficiently in battle by evading a barrage of attacks from some of his opponents and cutting half a dozen opponants with simultaneous 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 rectangular tsuba, which is chipped, likely showing that Ashido has been in many fights within the Menos Forest since the time he arrived. He has never released his Zanpakutō when he is shown. The extent of his skills and stages of Zanpakutō release are unknown.
 * Shikai: Not yet revealed.
 * Bankai: Not yet achieved.

Quotes

 * "It’s the Menos’ nesting grounds. A world far removed from where Soul Society’s laws carry any meaning."
 * "This is a fierce forest. The weak cannot survive here."
 * "In order to protect human souls, and keep the promise I made with those who lost their lives, I’ve stayed here and fought."
 * "I just wanted my friends to hear you speak. It’s been a while since they heard a Shinigami’s voice."
 * "Everyone chooses their own paths to follow."

Ashido Kanō