Jaren

"You should know more or less what let me become stronger... It's... the malicious hearts of humans. Humans' malicious hearts bring me power..."

- Jaren

Jaren (邪煉) is an evil spirit that constantly moves about in search of people to devour. Though very similar to an Ayakashi, Jaren is immune to any attacks that lack sufficient willpower.

Appearance
Jaren has a large, black, furry body, three large eyes, and a pointed snout.

Personality
Jaren is very skilled at discovering and twisting a person's beliefs to suit his own purposes. He typically drives his victims to the deepest level of despair, and then devours them. Exorcists are his traditional enemies, and while they possess the means to permanently seal him, the deeply personal nature of the exorcist's contract also makes them easy prey for Jaren if they show even the slightest bit of weakness. Jaren has even developed a taste for devouring an exorcist, allowing their comrade or disciple to pursue him, and eventually devouring them as well, restarting the cycle again.

History
Ten years ago, Jaren was restrained for a time by a powerful exorcist named Sagami, who formed an exorcist contract with Jaren and pinned down his body with many stakes. Sagami was a colleague of Kurogane, and had him to renew the contract, as Sagami was growing old. However, Jaren tricked Kurogane into freeing him and immediately killed Sagami, fueling Kurogane's quest to seal him.

Five years later, Jaren attacked young Takeshi Kongo, intending to eat him. Takeshi was saved by Kurogane, who managed to drive Jaren away and took Takeshi on as his disciple, though they did not began training together until three years later. However, only three days after that, Kurogane faced Jaren in combat and was consumed, leaving Takeshi to take up his master's quest of sealing Jaren.

Plot
Jaren first appears in Karasumori some time after Takeshi does. Both Takeshi and Yoshimori sense his presence, but disagree on who should handle it, eventually challenging each other. Takeshi overpowers Yoshimori and leaves him staked to a wall by his backpack, and proceeds to Karasumori alone to face Jaren. Jaren immediately appears, his back full of stakes from past battles. Jaren laughs that he likes Karasumori, and shows this by using his new-found power to eject the stakes from his body as Takeshi looks on in shock. Yoshimori (now carrying Takeshi's missing stake), Tokine, Madarao, and Hakubi arrive, only to get their first glimpse of Jaren before he escapes.

Jaren races around Karasumori Academy, commenting how much lighter his body feels, and that he hasn't felt so good in a long time. He had been carrying the nails in his back since the first exorcist he encountered bound him. Jaren decides he won't be satisfied until he eats Takeshi, and recalls that Kurogane was delicious. Madarao and Hakubi locate Jaren as he appears before the group. Jaren likes their concerned expressions and attacks, but Yoshimori knocks him away with a Kekkai. Jaren decides to deal with them slowly and runs away.

Jaren appears in front of Yoshimori, Tokine, and Hakubi. Yoshimori is impressed by the evil aura he senses, but Tokine feels suffocated, as if something is probing them, and warns Yoshimori to keep his distance. Yoshimori points out that he can't fight if he stays far away, and surrounds Jaren with a Kekkai. Oddly, Jaren does not seem alarmed, and Yoshimori is still able to sense Jaren's malice with through the Kekkai. Yoshimori watches in shock as Jaren simply walks out of the Kekkai, melting it away at his touch. Elsewhere, Takeshi is worried that if the Kekkaishi are continually exposed to Jaren's malice with no preparation, they will weaken easily.

Meanwhile, Jaren has dissolved his body into a black whirlwind and surrounded Yoshimori, who has surrounded himself with a Kekkai. Tokine and Madarao are unable to get closer, and Hakubi realizes that Jaren is targeting Yoshimori. Jaren laughs at the idea of Yoshimori protecting Karasumori, and Yoshimori responds that he never wanted to. Jaren replies that he shouldn't do it then, but Yoshimori insists he has to because of monsters like Jaren. Jaren suggests that Tokine could guard the land instead, but when Yoshimori points out that she is from another family, Jaren cruelly calls them both replacements: they work in a pair, so it doesn't matter if one should die, as there will still be someone to take over. He says that it had been that way for a long time, but Yoshimori simply never realized. Yoshimori refuses to believe him and says that there are other Kekkaishi, so Jaren immediately suggests there should be someone more suitable for the job, turning Yoshimori's thoughts to Masamori, and questioning why Yoshimori was the one selected. Yoshimori's will weakens, and Jaren instantly attacks him, melting through the Kekkai with ease. Jaren is then struck by Takeshi's stakes and driven back. Jaren begins to taunt Takeshi: he says that Takeshi isn't a real disciple because he only trained three days, and that Kurogane didn't deserve such loyalty as a man who harmed others to make his wishes come true. Takeshi recalls that Kurogane warned him not to be like himself, proof that at least some of Jaren's words are true. Jaren says this is because he ate Kurogane's heart, but Yoshimori says the relationship between Takeshi and Kurogane isn't something for Jaren to decide. Yoshimori and Tokine pummel Jaren with their Kekkai, causing him to flee.

Yoshimori and Takeshi continue to pursue Jaren, pummeling him with Kekkai and stakes. Yoshimori and Takeshi compliment each other on their attacks, and when Jaren dissolves and flees, they chase after him. Tokine and Hakubi chase after them, wondering what the pair could be thinking. She recalls that Takeshi has already told them that normal attacks are useless: Jaren will only dissolve and escape, manipulating the opponent until it devours their heart, leaving only an empty corpse. Yoshimori suggests that they maintain an overly positive attitude: Tokine dislikes this plan, but Takeshi agrees (likely because being overly positive is normal for him).

Yoshimori and Takeshi keep up their plan of attacking Jaren and staying positive, and Yoshimori notes that it seems to be working: Jaren is growing weaker. Despite this, he wonders why only Takeshi's techniques do any real damage. Takeshi says it is because Yoshimori's technique is not appropriate for fighting Jaren: the Kekkai technique is effective against physical beings, but Jaren is a spirit that has no solid form. Exorcist techniques, on the other hand, use the stakes as a focus to send power directly into the enemy's body, and in addition, the contract works almost like a curse.

Jaren suddenly stops running and confronts the pair. Tokine catches up and warns them to get away as she sees Jaren gathering power. Takeshi tells Yoshimori to get away as well, since he's not used to Jaren's malice, but Yoshimori claims that he'll only know if it's possible for him to fight Jaren if he gets closer. Jaren suddenly grows in size, and says he's stronger because of the malicious hearts of humans, which give him power. Jaren claims that Kurogane was especially tasty, and that every human has a malicious heart. Combined with the power of Karasumori, he laughs that they have no chance against him. Yoshimori is confused, because Jaren's words have no effect on him: from what Takeshi told him of Kurogane, he feels Jaren is mistaken about him. Takeshi realizes that Jaren is only focusing on a small part of the overall man that was his master, and knows that Kurogane truly regretted his crime, and hunted Jaren to make up for it. This makes Takeshi more determined to stop Jaren. Yoshimori surrounds Jaren with a Kekkai, and Takeshi throws a stake imbued with his power at Jaren. Jaren shrieks as he is struck, and Takeshi says he will bear all of Jaren, and commands him to kneel with an explosion of power. Takeshi proclaims the contract a success, and Jaren seems stunned before he dissolves and flees again, this time leaving Karasumori for good. Yoshimori is alarmed, but Takeshi assures him that Jaren cannot move too far away from his master, and that he will take care of Jaren slowly later on.

Power & Abilities
Heart-Reading: Jaren is able to see into a person's heart just by being near them, allowing him to read their thoughts to a certain extent.

Expert Manipulator: Along with his ability to read hearts, Jaren is able to twist a person's beliefs and weaken their will until they are vulnerable enough for him to consume.

Overwhelming Malice: Simply being in Jaren's presence exposes people to his malice, which seems to work in conjunction with his manipulation, gradually weakening them. Tokine describes it as a suffocating, probing sensation.

Spirit Resistance: As a spirit, Jaren can only be harmed by exorcist techniques fueled by a sufficiently strong will. Anything less has no real impact on him (Yoshimori's Kekkai are able strike him, but they cause no harm, and melt at Jaren's touch). He can also dissolve his body in an instant, which makes it very easy for him to escape risky situations.