Abyss Feeder

Abyss Feeders (深淵喰い, Shin'en Gui, literally "Abyss Eaters") are a weapon created by the Organization. They are created from the flesh and blood of Awakened Beings. Their purpose is to hunt down and kill Abyssal Ones, such as Isley of the North or Riful of the West.

Biology and Appearance
As mentioned above, Abyss Feeders are created using the flesh and blood of Awakened Beings. The Feeders are blinded, have their mouths sewed up, and only respond to nearby movement. They are designed to hunt down and destroy Abyssal Ones, like Riful and Isley, by tracking their scents like bloodhounds. They can also be sent after other creatures as well, seen when the Organization dispatched them after the Claymore's when they were rebelling.

It is unknown if male humans are used in this process as well, though there is no reason why there shouldn't be since Abyss Feeders cannot awaken. In fact, they are modified to not have any yoki at all, making them unable to be tracked or sensed even by sensory-type Claymore's. Because they have no yoki they are unable to sense it as well and rely on smell and hearing alone. It's also suggested that they have a "sixth sense" much like Miata has, as they are able to navigate across terrains and communicate with each other non-verbally. While the Awakened Being flesh removes all traces of humanity in these hybrids, the Organization has also removed all sense of self, forcing them to crave only the flesh of their target.

At any given time, the Organization tries to maintain 11 in the field. Dietrich mentions that the current 11 aren't the original 11. When their numbers fall in half, they are conditioned to return to the Organization. The missing-in-action are replaced.

While they do appear to have parts of missing armor and cloth, most of their skin is left bare. It also appears as if to prevent the armor from falling off it is sewn into their skin.

Abilities
The Abyss Feeders have a level of power not unlike a higher level Awakened Being, however, they have little-displayed power variation between individuals. They have an insane level of regeneration and very malleable bodies. However, they are also incredibly unintelligent and slow-witted creatures with little to no sapient characteristics, a strange feature as most other yoma Entities are sapient.

Yoki Absence
Abyss Feeders have no yoki, therefore they cannot awaken or use yoma power. This is presumably because their origin is from Awakened Beings instead of Yoma and instead gather their supernatural strength and speed from this. This also means they have a hard time sensing yoki as well, but because their target is meant to be Abyssal Ones they have no problem sensing this.

History
After the fall of Pieta, 11 Awakened Beings of Isley's army attack Organization headquarters. All are killed by Claymores No. 1 and 2 (Alicia and Beth). The bodies are used instead of Normal Yoma to create a new type of "Claymore." It is unclear if the tissue of Awakened Beings is being implanted into human females. But the non-appearance of male Feeders is suggestive.

Dietrich mentions that the current 11 aren't the original 11. When their numbers fall in half, they are conditioned to return to the Organization. The missing-in-action are replaced.

While they have been conditioned to learn the skills of their prey, and spread the information to other Abyss Feeders, this seems to be a totally artificial ability only possible by the Organizations manipulations. Also, being blind and relying on scent and Yoki sensing, they are at a great disadvantage against opponnents that are surpressing their Yoki.

Hunt for Isley
During the Seven Year Time-Skip, the Abyss Feeders hunted for Isley. When Helen, Deneve and Dietrich travel south through Mucha, they reached a town where they sense Isley's presence.

Dietrich warns Helen and Deneve about "Demons," but Helen and Deneve assume Isley is the "Demon." Ignoring the warning, Helen and Deneve visit the town anyway, hoping to catch a glimpse of Isley for a thrill. Isley sees through their disguise and attacks. Helen and Deneve fight for their lives. The Feeders interrupt the fight. Dietrich intervenes, telling Helen and Deneve to stay motionless, or the Feeders will attack.

The three escape, as the Feeders force Isley into his awakened form. He manages to slice a few in half but, thanks to high speed regeneration, they continue to fight on. They close in and begin to eat him alive.

Attack on Riful
The Abyssal Feeders lead Alicia and Beth to Riful. Together, they attack Riful and Dauf, one of the Abyssal Feeders ripped off part of Riful's head..

The battle was interrupted when the Destroyer shot out many parasitic rods. The Feeders chase after Riful, who kills some of the Abyss Feeders, but there were more who showed up. Unexpectedly, Alicia goes out-of-control, attacking and killing the Abyss Eaters. Nearby, Beth is unconscious, impaled with a large Parasitic Rod.

Yuma and Dietrich
Not far from the above battle, Yuma guards an injured Cynthia. Yuma detects the approach of Yoma-like creatures, morphing from the "Parasitic Rods." Yuma lures them away from Cynthia, but becomes trapped herself.

But Dietrich brings the Abyss Feeders.

After Riful is killed by Priscilla, the Abyssal Feeders lose track of their target. Dietrich finds them and uses a piece of Riful's dress to lure them to confront the Yoma threatening Yuma.

Dietrich reveals that Abyss Feeders are "immune" to Parasitic Rods (presumably because the feeders have no sense of self that can be taken over). Feeders infected by rods only lose the limit on their appetite. Instead of Riful, the Feeders now identify the Yoma as food.

Rebellion
In order to prevent the defected warriors from reaching the Organization's inner compound, a group of Abyss Feeders were sent out to engage them. Not having time to properly program them, this group had no specific targets and were simply meant to delay the rebellion's advance for as long as possible. According to Miria, they were to be considered more dangerous than even an Abyssal One. The difference in their power and the rebellious Claymores is great so only the single digits and the other high ranks are fighting them directly while the others are on support. In the end, the Abyss Feeders seem to be all defeated by the Claymores.