Sealing the Demon Dog

Sealing the Demon Dog (妖犬斑尾封印, Yōken Madarao Fūin) is the 12th episode of the Kekkaishi anime adapted by Sunrise.

Summary
"A figure named Kouya appeared at the Karasumori site. 500 years ago, he had been Madarao's friend and ally. But now, he was an Ayakashi. As Kouya drew on the vast power of Karasumori, Yoshimori was forced to release Madarao's forbidden seal. Back to their true forms, Madarao and Kouya began a terrifying battle."

- English dubbed Narration

The episode follows Madarao and Kouya's fight from the previous episode. Both Kouya and Madarao are wounded, heaving each others tail into one another chest. Kouya confidently calls Madarao foolish. As Kouya showed off his claws, he feels the pain of Madarao's deadly poison that was injected into him many times. Kouya realizes that the poison was brought on by Madarao's Silver Rain ability, which shot small, poisonous metal shards at him from his tail. After revealing that Madarao's poison can kill those who are already dead, he assures Kouya that both of them will die that night and that there's nothing stopping it. Finally, Kouya collapses. Madarao looks up at the full, shining moon. Kouya attempts to absorb more energy from Karasumori in an attempt to surpass Madarao's poison.

Yoshimori walks up to Madarao, disappointed that he'll let himself die this easily. Yoshimori reminds Madarao that he is his master, but Madarao simply denies it. Yoshimori confidently says that he wouldn't let Madarao die, ever. Madarao warms up to Yoshimori, complimenting him as he stands on his feet. He apologizes to Kouya, saying that he can't die yet. Kouya still assures that he won't die. Then, the scene flashes back to 500 years ago, when Madarao and Kouya are together. Madarao is on the ground, dying of starvation. Kouya gives him a piece of meat, but Madarao refuses, and silently dies. In a rage, Kouya runs through the forest, blaming the Humans for destroying their land and killing him. He finds a Human in the forest and forcibly bites his arm. However, the Human grabs his sword from his waist and kills Kouya in one clean hit. Back in the present, Kouya pledges not to die until he eats every last Human. While Kouya continues drawing in more power, Madarao and Yoshimori discuss a strategy.

Yoshimori walks in front of Madarao, and gets ready to produce a Kekkai. Kouya is disgusted with Madarao's loyalty to Yoshimori. Madarao reminds Kouya about the their cold code about submitting to the strong. Kouya launches his tail at them, but Yoshimori quickly creates four Kekkai, which is penetrated by his tail, slowing it down. He gives the cue to Madarao, who stabs Kouya in the back with his tail from underground. Madarao walks over to a dying Kouya, who wishes for Madarao to finish him off, claiming that the poison isn't working on him. However, Honetaro. Uhosuke, and Nagao come to Kouya's rescue. He shares his true feelings towards them, which saddens Honetaro to the point of almost crying. As Honetaro leaves with his friends, Yoshimori asks if he's sure. As Honetaro explains what he thinks of Kouya, he starts to cry. Kouya heartlessly tells them to go away. The three of them run away, crying. Madarao cannot kill him because he used up all of his strength already. Madarao asks Yoshimori to finish Kouya of for him. However, Madarao starts to summon the power of Karasumori. He sharpens his tail and delivers the fatal blow to Kouya, who dies peacefully after admitting that he wants to go back to their mountain.

Tokine and Yoshimori ponder on the strange powers of Karasumori as Kouya passes. Yoshimori puts the remains of Kouya in a paper and puts it away in his pocket. Tokine throws Yoshimori the seal, telling him that he has to seal Madarao quickly. Madarao slashes at Yoshimori, corrupted by the power of Karasumori. Tokine tells him to use Nenshi to tie the seal around Madarao's neck. Yoshimori summons Nenshi and throws it at Madarao, who hits it away. He tries to trap Madarao's legs with Kekkai, but fails. After many attempts, he gets a Kekkai on Madarao's foot and jumps on his back. He throws the Nenshi around his neck and begins to put the beads on it. Tokine finds a bead that Yoshimori left on the ground, but when she tries to throw it to him, she is shot down by Madarao. As Yoshimori puts the last of the beads in the Nenshi, Madarao roars and struggles,. Hakubi gives Yoshimori that last bead that Tokine had and secures it on the Nenshi. At home, Toshimori notices something weird going on with Madarao's rock in his doghouse and tells Shigemori, who knows exactly what happened. Yoshimori is surprised at Hakubi for caring so much; Hakubi claims that he doesn't like Madarao, but has to go by Tokimori Hazama's wishes. Yoshimori undoes his Kekkai as Hakubi said, and Madarao starts crashing into the buildings around them, trying to get Yoshimori off him. Tokine creates and destroys a Kekkai in Madarao's face, causing him to raise his head. Yoshimori successfully ties the Nenshi together, thus sealing Madarao.

After that, Yoshimori realizes that he's sitting on Madarao, and quickly apologizes to him. He thanks Tokine for keeping Madarao steady. Shigemori runs down to the site, yelling at Yoshimori. But when he gets there, he's stunned that Yoshimori was able to seal Madarao in the first place. Shigemori scolds Yoshimori after looking at all the wreckage. Tokiko walks to the scene, teasing both of them. During the clean up, Madarao regrets promising Yoshimori that he will be his master.