Ayakashi

Ayakashi (妖) (Demons in the English Dub) are creatures of the night. They hate light, preferring darkness. They are the main threat to Kekkaishi and Karasumori. It is a Kekkaishi's duty to defend the site from Ayakashi attack, either removing or destroying them in the process.

Ayakashi are supernatural creatures (though the term is most often applied to demons), and come in a variety of shapes and sizes, ranging in power from mildly annoying to incredibly dangerous. Nearly all sentient Ayakashi seek greater power, generally through means of force. Several stronger Ayakashi have a tendency to only reveal their true bodies in desperate battles, and take on human forms which they spend most of their time in. This supports the theory that the underlying desire for most or all Ayakashi, whether they realize or acknowledge it, is to become human. Because they are primarily creatures of darkness, most Ayakashi only appear at night. The few that can tolerate sunlight either have special abilities or considerable power.

The origin of many Ayakashi is shrouded in mystery, but a number of them were once ordinary living beings. Perhaps the most detailed examples are provided by Madarao, Kouya, and Hakubi. All three were living wolves that died prematurely: Madarao (then known as Ginro) died of starvation, Kouya was killed by a human, and Hakubi was consumed by a stream of dark power accidentally unleashed by Chushinmaru Karasumori. Madarao states that he was unable to pass on (which implies that he was a ghost at some point) and returned to his mountain home, by which point he had already become an Ayakashi. There he met Kouya, who had also been unable to pass on because his soul was in turmoil, and had also become an Ayakashi. Though no details are provided on Hakubi's past following his death, he, too, became an Ayakashi eventually. This implies that some ghosts may become Ayakashi over time, if unable to pass on for some reason (likely due to strong feelings of regret or anger). Exposure to excess power, such as that of Karasumori, clearly accelerates the process. Yoshimori also states that objects filled with a strong wish may become Ayakashi.

List of Ayakashi

Common
Most Ayakashi are of the least powerful variety (though this in no way means they are harmless): they are drawn to Karasumori in search of greater power, likely because they could easily be destroyed or cease to exist without it. Their primary goal is to obtain power from the site, which would allow them to transform into a stronger form with increased powers. Many of these Ayakashi at least vaguely resemble a recognizable type of animal, demon, or plant.

Humanoid
Ayakashi classified as humanoid tend to be among the most dangerous. A human form generally represents that the Ayakashi is suppressing its true form and power, but can shift back to its natural form to access its original, greater powers within seconds. One notable exception to this are former humans who chose to become Ayakashi. In that case, they may either retain their human form (Mudou), or permanently alter it in the process (Kaguro). In either case, they still represent a greater threat than normal Ayakashi, because they are more capable of strategic planning. However, in unusual cases (Kokuboro), Ayakashi use human skin disguises to go into Karasumori so that they are undetectable. Common Ayakashi use illusions or physically transform their entire body into their desired human form.

Ayakashi Majiri
One special case is people born with Ayakashi blood. While generally considered more human than Ayakashi, they still have access to Ayakashi powers, and some are even capable of fully transforming into an Ayakashi body that has no obvious human features. A great amount of control and willpower is required to master and keep a tight reign over these powers, or the user could risk being overwhelmed by their Ayakashi blood, causing them to become a mindless monster. This is especially a risk when exposed directly to Karasumori's power.

Bugs
There are a vast number of different species of Ayakashi bugs. The majority seen in the series were under the direct control of Byaku, who maintained a massive nesting ground in the lower layers of Kokuboro's castle.

Dragons
Dragons (龍, Ryū) are some of the rarest and most powerful Ayakashi in existence. At least some originated in the mystical land of Ryusenkyo, which is recognized as their home and known for producing people with extremely powerful Ayakashi blood.

Honshū Wolves
Honshū Wolves were named for one of Japan islands they inhabited. Though they are truly wolves, they are also called "mountain dogs." Honshū wolves are an extinct subspecies of the Gray Wolf, the ancestor of the domestic dog. Both of these relationships are evident in the wolves' appearance: their natural forms more closely resemble (and are even commonly called) dogs, with some wolf characteristics, but their transformed Ayakashi forms are entirely wolf-like.

Oni
Oni are a unique Ayakashi species in that they are able to form contract partnerships with human demon tamers. The contract is formed when the human gives the oni a name, as well as a charmed tool, which acts as a visible symbol of their bond and a means of nonverbal communication. Highly experienced demon tamers, however, appear able to communicate with large numbers of oni without using such a tool.

Tengu
Tengu (天狗) are a unique species of Ayakashi that have both human and avian characteristics. They are unaffected by sunlight, and reproduce by dividing their bodies. Tengu purposely live beyond the reach of humans, but are capable of human transformations in order to interact with them peacefully.