Pureblood

Purebloods (純血種, Junketsushu) are the highest rank among vampires classed as Level A (Aクラス, A Kurasu, lit. "A Class"). Their blood remains pure without any human contamination: they can trace their blood back to an original Pureblood ancestor. Purebloods all possess a series of unique powers, often exclusive only to the certain Pureblood or Pureblood family.

There are currently only seven Pureblood families: Kuran, Hio, Hanadagi, Toma, Shirabuki, Ouri, and Shoto.

Outline
A very long time ago, when the human race was on the verge of extinction the first vampires emerged. These first vampires, known as Purebloods, appeared. Purebloods are those who have not bred with humans, thus keeping their vampire blood pure. Some Purebloods breed with Humans producing weaker vampires which have came to be known as the Noble vampires. Most vampires have some human blood in them, but a Pureblood vampire does not.

War broke out between the Purebloods and the Humans at some point a long time ago. In order to defend themselves against vampires, some humans ate an ancestor's flesh, creating the vampire hunters which granted them the power and strength to kill vampires. This includes anti-vampire magic and weapons. Therefore all vampire hunters have vampire blood in them but not to the extent that they are classified as vampires, thus they do not benefit from a vampires longevity and thirst for blood. The vampire hunters protect the Human race from the vampires.

During the war, the Pureblood population greatly diminished. Many Purebloods drank the blood of humans during this time thus creating Level E vampires to increase the vampire population. Consequently, there are few Purebloods today.

Powers
The full extent of their powers are only known amongst their Pureblood companions. Their true powers remain a mystery. They have ethereal beauty of the Purebloods. They are immortal, meaning they live forever unless an anti-vampire weapon is used to cut off their heads or pierce their hearts. Any other injury is healable, including having one's head cut off or blown to pieces, if a Pureblood uses the blood of another Pureblood to heal them. When a Pureblood vampire is killed, their bodies slowly disperse into small sparkles before shattering into shards of glass.

It is heavily implied that each vampire has a unique power such as Rido Kuran's ability to manipulate his blood or Shizuka's control over plants. Their blood is highly prized and many have attempted to drink their blood, this includes both humans and Noble vampires. The blood of a Pureblood can grant them new powers. Aside from the standard powers shown by other vampires, Purebloods have also demonstrated the following: The Kurans are unique among Purebloods, as some members of the family possess and display the ability to handle anti-vampire weapons. Juri Kuran, Yuki Kuran, Kaname Kuran (although he can hold such weapons, it does harm him) and Rido Kuran have demonstrated this ability.
 * They can form shadow puppets/spies using parts of their flesh which are capable of shape shifting.
 * Powers to perform spells to seal off the vampire side of vampires, thus making them a normal human. The spell also erases all of his/her memories of being a vampire. However this spell comes at the price of their life. (The vampire converted to human, eventually must return to his/her true nature, if not, he/she descends into madness. However, this was only in Yuki's case as Isaya said his son died human)
 * Ability to control lower vampires physically.
 * Erasing Memories.
 * Telekinesis.
 * Ability to Possess the Bodies of Other Vampires.
 * They can also put themselves to sleep for a very long time, even hundreds of years, and be resurrected through a blood sacrifice. Purebloods can become each other's masters if one is awakened by another from slumber.
 * Increased sense of smell.
 * Increased strength and speed.
 * Ability to turn humans into vampires and retain complete control over them by becoming their master, rendering the vampire unable to kill them. The blood of their master, will also prevent an ex-human from becoming a Level E vampire.

Relationships between Purebloods
Purebloods tend to not show emotion (Yuki Kuran is an exception to this as she had lived as human, and thus doesn't want to bottle up her feelings) and are wary of other Purebloods.

The Pureblood nature is an everlasting quest for power. By killing and drinking the blood of another Pureblood, they can absorb their power. However, this is a great taboo and is said to summon a sinister future upon that Pureblood, unless it is their lover. Similar to other vampires, a Pureblood's blood thirst can only be quenched by the blood of their loved one. Since Purebloods live for eternity, losing their loved one is much more devastating for them.

It is also common practice for Pureblood siblings to marry each other to preserve their thick blood. For example, the Kuran family, who are at the core of the vampire world.

Relationships between other vampires
Relations between the Purebloods and the Nobles are mixed. Noble vampires who are Pro-Monarchy have a strong sense of loyalty to Purebloods as seen by Aido who refers to Kaname as "Kaname-sama" (Respectful and formal Japanese term) and always protects Yuki. It is very important for Purebloods to continue the vampire race, therefore many Noble children are put forward as potential wives or husbands. As opposed to other vampires who are Pro-Vampire Council view the Purebloods as a threat because of their great power; for example Asato Ichijo wanted to rid the world of Purebloods because they have the power to absolutely control lesser vampires will. However, no matter what a vampire's political views are, they all have a seemingly instinctual fear and awe for Purebloods. The Purebloods and the Vampire Council also work together in order to maintain order in the vampire society by keeping watch over Level Ds and exterminating Level Es.