Asarakam

A sentient race also called "Dragon's Kin" or "Descendants of Dragons". In their original form, they look like slender but muscular humanoids with dark flesh and an organic armor while their transformed state is that of towering beasts with a human visage but covered in impenetrable scales and armed with sharp claws: it is this primal appearance that earned them the moniker of "Dragon's Kin".

History
After a battle with Yoma in Rabona, Miria has a meeting with her comrades.

She reveals the existence of "an even greater land outside of this one," where a war rages between two sides: one side which controls the Organization, and the other side, who are related to Dragons.

Little is known about the creatures, other than their "extremely tough skin". Miria refers to the creatures themselves as the "Descendants of Dragons". When confronted by Mira, Rimuto refers to the Dragon's Kin as the Asarakam. In their original form, the Asarakam are humanoid hermaphrodites roughly twice the size of normal humans. They have two eyes (plus a third vertical eye in their "pre-awakening" form), two arms, two legs and a lifespan of 200 years, increasing in strength throughout their lives. The Asarakam can "awaken", becoming large monster-like beings with armored scales and destructive powers and, similar to the Claymores, once "awakened" they can never revert back to their original state. Both forms of the Asarakam necrotize rapidly when killed, but by combining slivers of flesh taken from two Asarakam that had been captured and put in suspended animation, the Organization created a parasite capable of turning humans into the carnivorous monsters called Yoma. Since the Yoma and Awakened Beings have some Asarakam genetic component, it's well possible that the Asarakam themselves have purple blood like both.

Theories
The Dragons' Kins are shrouded in mystery as little is known about them as a race or their motivations in participating in a war between humans. They are referred as "Asarakam", an ancient Pali word that means "empty", but it is unknown how they earned this name: it can be a simple derogatory term to assimilated them to savage beasts or possibly to hint to a totally amoral mindset. If the latter hypothesis is true, it is well possible that they joined forces with a human faction just to feast on fallen enemies. Indeed, as both Yoma and Awakened Beings (both are genetically related to the Asarakam) are anthropophagi in nature, the Dragons' Kins could be something akin to the natural predator of the humans.

The only certain thing about their biology is that these creatures are born with monstrous strength, resilience and regenerative powers (the Organization created the Awakened Beings to even the sorts of the conflict but without thinking to best them on the field for sure), but their bodies sport gills, scales, and fins, all signs that paired with their purple blood could betray an aquatic origin.

Trivia

 * The VIZ manga translation makes no reference to the "Dragon's Kins," and refers the Draconic Tribe as the "Dragons' Descendents" instead.