Abyss Feeder

"Abyss Feeders" (深淵喰い, Shin'en Gui, literally "Abyss Eaters") are a weapon created by the Organization, made 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

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.

The result are warriors that have no trace of humanity left. The Organization destroyed their eyes, bound their mouths and removed all sense of self, forcing them to crave only the flesh of their target. They are modified to release no Yoki, which inhabits their ability to sense it.

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.

The Abyss Feeders weak points are their heads. They have high regenerative abilities. However, new Abyssal Feeders that lack experience are far less powerful than their full potential. In a battle, the new Abyss Eaters will continue to gain experience as the fight goes on, making them harder to kill.

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 Ritful's head..

The battle was interrupted when the Destroyer shot out many parasitic rods. The Feeders chase after Ritful, 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.