Vampires

Vampires (吸血鬼,) are an immortal race of humanoid beings that feed on the blood of humans. A human who ingests vampire blood becomes a vampire. Vampires have fangs, pointed ears, and red eyes. Until drinking human blood, the vampire may age and retain his/her original eye color. Vampires do not retain strong emotions from when they were human and gradually lose more and more of their humanity. Despite being former humans themselves, vampires look down on humans and consider them nothing but mere livestock. They dislike increasing their numbers and very rarely turn a human into a vampire. A vampire's power is dependent upon both age and lineage.

Drinking human blood is insanely pleasurable to them, especially right from the source. Vampires can also enjoy drinking vampire blood, but the details and limitations of this have yet to be revealed. Mikaela lives off of Krul's blood for four years before it is no longer effective at quenching his thirst.

Vampires typically only care about blood, and those who are concerned with other things are considered to be eccentric. Ferid is considered to be eccentric, and Mikaela even more so. As they have gradually lost their human traits, vampires band together out of their own self-interest and not out of affection or love for one another.

When a vampire is killed, he/she turns into ashes.

A vampire who starves does not die but rather becomes a demon.

Progenitors
Progenitors are shown to be the same as royalty among the vampires. All progenitors are nobles but all nobles are not necessarily considered to be progenitors. They are quite powerful, and this power increases with greater rankings. However, progenitors of the same ranking are not necessarily equal in power. Progenitors ranked 6th and better have the right to attend meetings of the Progenitor Council. It is likely that the vampire queens and kings around the world are all high-ranking progenitors of a very high lineage.

Not shown:
 * 2nd Progenitor Waldo Gilles
 * 3rd Progenitor Gable Fatima
 * 17th Progenitor Zane Lindau

Nobles
A human turned into a vampire by a progenitor becomes a noble. The nobles are high-class vampires who are far stronger than the average vampire and wield stronger weapons. There are 20 ranks of nobles.

Common Vampire
Common vampires are vampires who are not of nobility. They seem to be weaker than the higher classes, but remain stronger than humans. A common vampire with greater battle prowess has influence similar to a lower-ranked noble.

Laws

 * Vampires are forbidden from any meddling with the Curse of the Seraph.
 * Prior to the Apocalypse, vampires were forbidden from meddling with human affairs. This law was overturned once the human population became threatened, and vampires rose up to save their food supply.
 * In the city, vampires are forbidden from drinking blood directly from a human. They may only drink blood directly while on the surface or on the battlefield. This is because more vampires tend to drink their prey dry than not.
 * Drinking blood from another vampire is forbidden but grants immoral pleasure.
 * Only nobles are permitted to turn a human into a vampire.

Aging
A newly-turned vampire can survive off of their sire's blood and will continue to age until drinking human blood, but this will only work for a limited period of time. Once the vampire drinks human blood, the vampire's biology stops completely, and the vampire grows tremendously in strength and power. By drinking human blood for the first time, a vampire evolves into a true vampire and will complete the transformation.

Natural Abilities
Vampires have impressive power and regenerative abilities; this increases with their lineage and age. They can easily reattach a limb. Nobles have the authority to turn a human into a vampire if they so choose. Vampires may increase their abilities by drinking human blood at any time.

Their eyesight allows them to distinguish a target several hundred meters away, even in pitch-black darkness.

Weapons
In battle, they use their natural abilities as well as different types of weapons. Second-class weapons are used by common vampires, and are not as powerful as first-class weapons. First-class weapons pierce a vampire's hand and drink vampire blood in order to significantly increase their power.

The nature of the first-class weapons is unknown.

Protective Gear
Vampires most commonly wear armbands on their left arms to protect themselves from UV light. They may also wear rings. This allows them to move under sunlight without harm, although they still dislike it.

Weaknesses

 * They have immense pride and typically underestimate their human opponents or may refuse to work together with vampires of rival factions.
 * Sunlight! Exposure to UV light will create a toxin in their bodies, and vampires must wear protective gear to neutralize this effect.
 * They can be killed if their heads are destroyed. One bullet will not do the job.
 * Cursed gear and enchanted gear used by the Japanese Imperial Demon Army limit their healing capabilities.

Trivia

 * They typically refer to the humans as "livestock" or "humans" instead of calling them by their names.
 * Yūichirō Hyakuya reads a book in chapter 1, which states vampires are merely 7x as strong as humans. Considering a vampire's ranking, this can be a severe underestimation.
 * Krul, Chess, and Horn either have small horns or horn-like decorations on their heads.