The Mystery of Karasumori

The Mystery of Karasumori (烏森の謎, Karasumori no Nazo) is the 39th episode of the Kekkaishi anime adapted by Sunrise.

Summary
"During the battle with the Ayakashi organization, Kokuboro, Gen Shishio lost his life. As Yoshimori and the others mourned the loss of their friend, they were overcome with sadness"

- English dubbed Narration

The episode begins with a depressed Yoshimori who, miraculously, isn't asleep in class. Hiromu Tabata points this out, Tomonori Ichigaya asks Yoshimori if he's okay, but he gave no response. Hiromu begins talk about the rumors that Gen changed schools, assuming it was a family thing. He asks Yoshimori if he knows anything, but he again gives no answer and leaves the room. He goes up on the roof, stopping at the top of the ladder to observe the lonely roof without Gen there. As he gets up, he remembers when Gen startled him with his claws when he was trying to tell him to move. Meanwhile in Kokuboro, Sakon examines his former commander's chambers, walking to his desk and taking a seat. He spots Shion, who suggests making his chambers more fitting to himself. Shion had her Pink Silk wrapped around his collarbone, testing him. Hekian goes to report to Byaku his findings about the landlord of Karasumori. He claims that he's found the whereabouts of the land lord. He, Sakon, and three others from task force one, go to the Colorless Swamp and examine it. Hekian uses his Thousand Eyes to look past the water into Lord Uro's dimension. Sakon orders two of his henchman to fetch Nomori, a large snake-like Ayakashi that has an unquenchable thirst.

Next morning at Karasumori Academy, Tokine is too distracted looking at the window, possibly too upset about Gen, to answer a question in class. She honestly tells her teacher that she wasn't listening, which startles him, making him worry that he's a failure as a teacher. Kirara Kawakami asks Tokine if she's all right at the end of class. She mumbles something about Gen to herself, which catches Kirara's attention. Tokine assures her that nothing is going on and that she's just tired. Meanwhile, Yoshimori spends another depressing class alone, Hiromu mentions that he's about to break a record for consecutive days awake, which just angers him. Tomonori tells Hiromu to change the subject, so he takes out his phone and plays the news about all the water disappearing from the Colorless Swamp. Yoshimori and Tokine quickly head down to the Swamp, when Tokine shows signs of distress because of her skirt, Yoshimori helps her get through the grass by knocking down small bushes and trees so it'll be easier for her to walk. Yoshimori calls for Lord Uro in a massive hole in the middle of the swamp. Mamezo appears behind him, using the vine on his head to push Yoshimori into the hole. Tokine mentions Kokuboro, which only confuses Mamezo. He mentions Princess and Kurosusuki.

At the Sumimura Home, Yoshimori reports his findings to his grandfather, who is relieved to hear that Lord Uro is safe. When Yoshimori mentions Kurosusuki, he is chopped on the head, and had an X and O drawn on his face. Shigemori shows how to write Kurosusuki, saying it was part of The Other World. Hekian reports back to Byaku, He reports that even though Lord Uro eluded their attempt to summon him, they did fall upon an Ayakashi raccoon that has been living in the Colorless Swamp for quite some time. Hekian agrees to go investigate Karasumori himself, saying that he won't bring anyone along with him. That night at Karasumori, Yoshimori and Tokine pursue an Ayakashi with a black, shadow like body. Once captured by Yoshimori, he attempts to interrogate it. With no luck, he destroys the Ayakashi and then Tokine uses Tenketsu to send it to another world.

Immediately afterward, Madarao and Hakubi sense another Ayakashi. The Kekkaishi follow and soon find Hekian waiting patiently. Hekian notes that it took a while for them to defeat such a low-level Ayakashi, and Tokine realizes the first one was a decoy. Yoshimori attacks, but Hekian easily avoid his Kekkai, and seems more interested in learning about the technique than avoiding it. Yoshimori moves to chase him, but suddenly finds that all of their shadows have been pinned to the ground by Hekian, which prevents them from moving. Hekian explains that he has no desire to harm them, and that he is continuing his research from the Colorless Swamp. He uses his Thousand Eyes on the ground at Karasumori, and is overwhelmed by the deep darkness that he finds. Hekian asks Yoshimori if Kekkai can manipulate space. Yoshimori refuses to cooperate. Clouds briefly pass in front of the moon, breaking Hekian's spell. Yoshimori instantly attacks, but Hekian's speed is still far greater than his. After taking a moment to study Yoshimori's large Kekkai, Hekian decides the trip was worth it just to see the Kekkai technique in action, and vanishes after saying Kokuboro will take over Karasumori. Tokine notes that Hekian's spell only worked in direct moonlight. Madarao and Hakubi confirm that Hekian has left, and Yoshimori is angered by Hekian's confidence.

Back in Kokuboro, Byaku talks with Princess, who claims to be bored. Hoping to improve her mood, Byaku shares Hekian's findings: there is another world beneath the Karasumori site, crafted by human hands, most likely a powerful Kekkaishi. He explains how protecting the site is passed down through generations of Kekkaishi to those who bear the Houin Mark, which is proof of their curious bond with the land. When Princess doubts a human could have created Karasumori, Byaku compares a Kekkaishi’s power to her own: she was able to create and shape Kokuboro simply by living there for an extended period. Princess decides that she finds Kekkaishi interesting after all. Byaku tasks Sakon with preparing the army for the next attack on Karasumori. Sakon says he is eager to avenge Gagin.

Both Yoshimori and Tokine resume their usual behavior at school the next day: Yoshimori sleeps in class, and Tokine is able to answer her teacher correctly. At Karasumori that night, Yoshimori and Tokine decide not to be caught off guard again, and rededicate themselves to protecting Karasumori from Kokuboro.

Differences from Manga

 * In the manga, Gagin accompanies Hekian to the Colorless Swamp and drains the water himself.
 * In the manga, Hekian does not go to the Karasumori site to question the Kekkaishi about the Hazama-Ryu Kekkai technique.