Yoshimori and Kaguro

Yoshimori and Kaguro (良守と火黒, Yoshimori to Kaguro) is the 51st episode of the Kekkaishi anime adapted by Sunrise.

Summary
"Locked in a furious battle with Kaguro, Yoshimori activates his still incomplete Zekkai."

- English dubbed narration

Shion watches the battle between Kaguro and Yoshimori, and from the amount of damage being to the surrounding buildings by Kaguro's attacks, expects Yoshimori to lose. Despite being at a disadvantage, Yoshimori encourages Kaguro to keep fighting. Kaguro asks for a break, saying that the longer they fight, the stronger Yoshimori gets. He is particularly interested in seeing Yoshimori's Zekkai once it's complete. Kaguro recalls how when he was still human, he saw a complete Zekkai once. Kaguro admires that Yoshimori doesn't hesitate to use his power, and thinks they are similar because they both constantly seek greater strength. Kaguro tells Yoshimori to become truly strong, he must throw away everything else in his life and become completely alone. He invites Yoshimori to join him, but Yoshimori refuses, pointing out that by asking for an ally, even Kaguro doesn't want to be alone, and that he could never side with someone who threw away their humanity. Suddenly, the castle begins to collapse around them, and in the confusion, Yoshimori is grabbed by Sen. Shion notices that the castle is breaking down more quickly now.

Masamori's search party makes their way through the portal. Shigemori tells what little he knows of Kurosusuki's demon fox: that she has a human form, and transformed the dimension into what it is now. Yoshimori is surprised to find himself in a Kekkai with Sen and Tokine. They're both angry at him for not having a plan to defeat Kaguro, and tell him that just charging in won't work against Kaguro's power. Tokine uses broken blades from Kaguro's sword to show that the sharper the blades become, the more easily they pierce through Kekkai. Sen adds that Kaguro's last attack was so strong, Yoshimori's Zekkai didn't break the sword at all. Yoshimori says he knows all that already, but Sen insists that he's in over his head, since he can't even use Zekkai properly. Sen explains that he saw Masamori's Zekkai once, and it destroyed any part of the enemy that it touched. Yoshimori finally says he can't give up because Gen would laugh at him. Kaguro's next slash slices off the top of the building the trio are hiding in, even from a distance. Yoshimori pushes Tokine toward Sen, apologizes, and goes to fight Kaguro again.

Kaguro charges with his strongest attack yet, and Yoshimori braces himself with his Zekkai armor. Suddenly, Sen dives between them, attempting to use a broken piece of Kaguro's sword to block the hit. As Sen's blade piece begins to break under Kaguro's attack, Yoshimori instinctively activates Shinkai for the first time, bathing the area in a bright blue aura. The shockwaves from the Shinkai even reach Masamori's search party, causing them to worry and increase their speed. Kaguro is stunned to realize he's going to lose, and wonders why. Shortly after his sword breaks through Sen's, Kaguro's body is vaporized. Sen is completely shocked, unable to figure out what happened. He notices that Yoshimori isn't moving, and wonders if what he's seeing is a Zekkai.

Princess is amused that Yoshimori used the power she gave him to protect, rather than destroy, but notes that she has shortened her life. Byaku rises, amazed that his wounds are healed. His first thought is of Princess, and he goes to find her. As Masamori's search party nears the portal exit, Hakota spots Yoshimori, Sen, and Tokine with his enhanced vision. They finally enter the dimension, and are able to see Yoshimori's shinkai from a great distance. Tokine calls to them, and Mukade sends one of his shadow bugs to pick her up. Masamori calls out to Sen, who tells him that something's wrong with Yoshimori: he isn't responding or even breathing. Shigemori assumes that Yoshimori put too much pressure on his body. Masamori tries to force the Shinkai apart with his Zekkai, and tells Sen to hit Yoshimori, in hopes that he'll wake up. Tokine knows that Yoshimori wouldn't hesitate if he were in her place. She decides to use her phasing ability on the Shinkai and dives toward it.

Differences from Manga

 * Because virtually no one still alive had seen a Shinkai before this point, there was considerable confusion as to its proper name. In the manga, Masamori refers to Yoshimori's Shinkai as a Kekkai. In the dub, Shigemori calls the encounter a battle of two Zekkai.
 * In the manga, Yoshimori's Shinkai is dispelled through a combination of Masamori's Zekkai and Sen stabbing Yoshimori with his claw.