The Spy

The Spy (sometimes referred to as the Observer) (監視者, Observer) is a Kokuboro agent assigned to observe Karasumori and the Kekkaishi who protect it. He is given a human skin disguise and command of Shirahago by Byaku. During his mission, he is forced to use an experimental serum that that eventually exhausts his body to the point of deterioration, resulting in his death.

Appearance
The spy is the first to use the Q-type human skin disguise (one of Aihi's first models) to conceal his Ayakashi aura and body. It takes the form of a red-eyed man with dark blue hair and pale skin, dressed in a business suit. The basis for the Q-type's appearance is a man that Aihi once lived with. Though only briefly seen, the spy's actual body is dark green and skeletal.

Observing the Kekkaishi
The Spy arrives in Karasumori intending to observe the Kekkaishi. To achieve this, he orders the Shirahago triplets to serve as distractions, but not to attack until he gives the signal. During the encounter, he takes note of the properties of Kekkai, Karasumori's influence on Ayakashi, as well as the individual strengths and weaknesses of Yoshimori and Tokine. Though Tokine manages to destroy one triplet, this enrages the remaining to, and with Karasumori's power, they are still able to transform into their giant owl form. Watching the Kekkaishi struggle against the owl, the spy begins to believe they will conquer Karasumori even though they were only sent to observe. However, thanks both to Yoshimori's power and Tokine's ability to adapt her Kekkai into spears, they are able to defeat the owl. Despite this, the spy assumes the Kekkaishi are no real threat. Tokine's Shikigami bird then spots him. Though he destroys it, the Kekkaishi sense his evil aura in the process. In addition, his human disguise begins to melt, and he flees as Yoshimori pursues him. In desperation, the spy uses an experimental serum that greatly boosts his power, and destroys the surrounding forest to cover his escape. He meets his superior Byaku nearby, though instead of accepting the spy's report verbally, Byaku withdraws a worm from his head and absorbs it, obtaining his knowledge in the process. Byaku then reveals the serum caused extensive damage to the spy's body, and casually leaves him to die as he collapses.

Powers & Abilities
Extending Arm: His true arm is extremely long and thin, and tipped with sharp talons. He can use it as a whip, building up speed to increase his slashing power, and rip through a target at great distance. He is also strong enough to uproot several trees at once, just by wrapping his arm around them.

Trivia

 * The Q-type human skin disguise is later used by Hisui, Kaguro , and Shion , which causes some confusion for the Kekkaishi and especially their dogs, since the disguises all have the same human scent. Aihi is later revealed to have several more copies in her lab, indicating that she put the Q-type into mass production before moving on to the next model.