Hekian

While he is one of Kokuboro's weakest fighters, Hekian (碧闇) is a skilled information gatherer. He is tasked with unraveling the mystery behind Karasumori, and reveals several important clues to the puzzle.

Appearance
Hekian always wears a green cloak and dark green necklace, as well as a pale green face wrap and a white turban that conceals his face. His style of dress and attitude are very similar to The Shadow Organization's Okuni.

Personality
Hekian's entire purpose is to investigate: the deeper the mystery, the more pleased he is while exploring it. He is especially intrigued by the Kekkaishi's Kekkai. Hekian appears to get along well with Koshu, and generally treats everyone (even enemies) with respect unless thoroughly provoked. He later reveals that this attitude was partially due to Byaku's mind control: once free of Byaku's bug, Hekian's attitude and speech are less formal.

Unraveling the Mystery of Karasumori
Hekian is tasked with uncovering the mystery of Karasumori, specifically finding a way to replace the current land lord with the Princess. Hekian and Sakon go to the Colorless Swamp, where Hekian uses his Thousand Eyes to confirm the presence of the god's dimension. Sakon uses Nomori, a giant worm Ayakashi, to drain all of the water, and then uses his Uzuyami in an attempt to break through (in the manga, it is Gagin who assists Hekian by drinking the water, instantly evaporating it inside of his body ). Unable to access the god's dimension, Hekian instead interrogates a raccoon Ayakashi that has lived in the area for some time. He discovers that ownership of Karasumori passed from Lord Uro to the current master, and decides to investigate the site directly.

Hekian goes to Karasumori, using a lesser, shadow-like Ayakashi to draw out Tokine and Yoshimori. He uses Kagenui in the moonlight to trap them while he uses his Thousand Eyes to peer into the ground, but is overwhelmed by the darkness that he finds there. Yoshimori manages to break free when clouds pass in front of the moon, and after briefly studying the Kekkai technique, Hekian leaves, pleased with his findings.

The Captive Kekkaishi
Shion has trouble suppressing Yoshimori's power and will after bringing him to Kokuboro's castle, and she asks Hekian if all the trouble is really necessary. Hekian assures her that it is: because Yoshimori is a Kekkaishi, he should have the innate ability to restore damaged space (such as Lord Uro's bed), and therefore be capable of restoring the damaged parts of the castle, and the dimension itself. He sees Yoshimori's success in resisting their control as proof of power, but wonders how Shion was able to capture him since she is unable to touch him. Byaku orders the captured Sen Kagemiya to be brought in, and Hekian immediately notices that Sen is an Ayakashi Majiri, not a Kekkaishi as Shion was ordered to bring. Shion claims she didn't know. When Byaku threatens to harm Sen if Yoshimori doesn't submit to him, Yoshimori lashes out with a powerful aura, destroying his restraints and Byaku's control bug. After Shion binds Yoshimori again, Hekian warns Byaku that Yoshimori's ability to repel could be dangerous for the castle. Byaku orders Hekian to have Aihi devise a method to extract Yoshimori's special powers, having given up on controlling him.

Hekian and Koshu discuss the capture of Yoshimori. Hekian remains confident in Yoshimori's ability to restore the castle. Koshu insists that Yoshimori must be controlled for the sake of the castle. He explains that the castle's condition has greatly declined in the last 300 years, though Hekian doesn't realize by how much, since Koshu has been with Kokuboro longer.

Careful What You Wish For
While the dimension of Kokuboro is collapsing, Hekian finds Shion and attempts to negotiate with her, offering to lead her to one of the remaining stable exits if she will offer him protection. Shion is insulted that he considers her an equal, and turns him into one of her spider goons. He apparently retains some of his powers, as Shion entrusts him with the task of leading her group to safety.

Powers & Abilities
Thousand Eyes (千重-眼, Senjuu-gan): Hekian's signature ability: purple eyes emerge from several places on his right hand, and can see through nearly anything. Notable exceptions are Lord Uro's dimension (because he is a god) and the alternate dimension beneath Karasumori Academy (because it is "a distant darkness carved by a human hand"). Presumably, Hekian retains this ability even as one of Shion's spider goons.

Kagenui (影縫い, Shadow stitching): Pins a being's shadow to the ground and keeps them from moving. There must be a light source present for this to be successful, and if it becomes blocked even momentarily, the technique weakens.

Expert Analyst: Hekian is extremely resourceful in terms of gathering and studying information.

High Evasion: According to Madarao, Hekian is very good at hiding his presence. He can also move with considerable speed in a way that resembles teleportation.

Trivia

 * By the way that Hekian and Koshu address each other ("Hekian-kun" and "Koshu-san"), Hekian is both younger than Koshu, and has not been in Kokuboro as long as him.
 * Hekian's name means dark blue in Japanese.