Black World

"Black World" (黒の世界, Kuro no Sekai) is the eleventh episode of the Kyoukai no Kanata anime series, released on December 11, 2013. It was storyboarded and directed by Ichiro Miyoshi, with animation direction by Nao Naito.

Synopsis
Mirai begins her assault on the dreamworld of Beyond the Boundary. However, the youmu quickly retaliates, forcing Mirai onto the defensive. Meanwhile, Mitsuki checks up on Akihito, only to hear of his concern for Mirai's well-being. Soon, Akihito learns what he needs to know from Hiroomi, including his three months in a hospital bed and Mirai's "disappearance." Akihito tells Hiroomi of rumbling sounds he has been hearing since waking up. Unable to hear these sounds due to his weakening powers, Hiroomi decides to bring Akihito to the Shindou Photo Studio.

Akihito eats a hearty feast of omelette rice care of Ayaka's cafe. Meanwhile, Ayaka tells Hiroomi that the sounds Akihito are hearing may be a side effect of his connection with Beyond the Boundary. Soon, Akihito urges Hiroomi to take him to Izumi, but Hiroomi refuses. Hiroomi reminds Akihito that he and Mitsuki had tried and failed to make Izumi tell the truth and an argument between friends almost breaks out. Only Izumi's arrival calms down both parties.

Outside, Izumi explains about the myth about Beyond the Boundary, calling it as a natural force that represents mankind's resentments accumulated over time. She found it shocking that such a powerful youmu would reside inside his body, turning him into a threatening "immortal half-youmu," so she decided to have someone with cursed blood (i.e., Mirai) destroy it. However, Mirai eventually chose to save Akihito and sacrificed herself.

Amidst Akihito's anger, Izumi thanks Mirai for saving the world.

Izumi's words shake Akihito. He wanders across town at night, his mind filled with memories of that dreamworld, and ends up at Mirai's apartment, where a furious Sakura asks for Mirai's whereabouts. He heads back home for the first time in three months, and finds Mirai's last text message for him.

''"I don't know whether or not you will receive this text, Senpai. At the moment, I don't even know if you'll ever read this letter. Senpai, it's Mirai Kuriyama! After I send this, I'll be on my way to go see you, Senpai. I'll go... and defeat Beyond the Boundary. I feel very strange right now. You see, I'm kinda happy! I was born to a clan with cursed blood, which gave me nothing but hardship. I always asked myself, 'Why was I even born?' Somewhere, a part of me wanted to die. But I was wrong to feel that way. I'm glad I was born! People say that my powers are cursed. People say they detest my powers. But I've come to realize that my powers aren't meant to hurt others! They're meant to save people! I'm glad I've lived this long. I'm so happy I'm not dead! I'm truly glad that I came to this town and met you, Senpai. I was much, much happier than I ever realized! I was never cursed! Senpai? Senpai, you can die like a normal person now. So... so from now on, please lead a normal life. Live, just like you told me to back that one time.

Senpai? I... don't feel unpleasant."''

Akihito is moved to tears upon reading Mirai's message. However, grim things are yet to come, as Miroku reveals that Beyond the Boundary, in its drawn-out fight against Mirai Kuriyama, is currently draining away the powers of all youmu and Spirit World Warriors in the vicinity. Miroku then decides to give Beyond the Boundary a boost to provoke Izumi Nase into action.

With a turn of his car key, he transfers the energy of his car into his weapon, which fires a beam that transforms the dimension of Beyond the Boundary into a black sphere visible to the eyes of normal humans. Soon, youmu are sucked into Beyond the Boundary. Meanwhile, someone summons Akihito to the school using flyers for the Literary Club.

Mirai continues to protect the Akihito within Beyond the Boundary. Outside, Hiroomi, Mitsuki, Sakura and Shizuku meet Akihito on the way to the school. As they see countless youmu being pulled up into Beyond the Boundary, they head to the school premises, only to find a gigantic suit of armor inside. To Akihito's annoyance, it's actually his mother, Yayoi Kanbara.

Yayoi tries to explain the situation while scantily dressed, and soon points to the stone Mirai acquired during the Hollow Shadow incident. To their surprise, the stone is actually part of Akihito that was dislodged when Mirai stabbed him; thus, it is a part of Beyond the Boundary. Yayoi's plan includes allowing Akihito to fuse with the piece of Beyond the Boundary and to capture his "puppet self" that is inside the youmu. Izumi leaps into the Literary Club room to warn Akihito about being a normal human, but Akihito pushes through nonetheless.

With Beyond the Boundary's stone in hand, Akihito launches himself into the youmu's realm and fuses with his "puppet self" within before running towards Mirai. Akihito manages to catch her after she deals a decisive blow to Beyond the Boundary and the two finally talk face-to-face after three months apart.

Characters
By order of appearance
 * Mirai Kuriyama
 * Akihito Kanbara
 * Miroku Fujima
 * Mitsuki Nase
 * Hiroomi Nase
 * Ai Shindou
 * Ayaka Shindou
 * izumi Nase
 * Sakura Inami
 * Shizuku Ninomiya
 * Yayoi Kanbara

Unanswered Questions

 * What was Miroku's plan behind empowering Beyond the Boundary?
 * How did Yayoi acquire so much information about Beyond the Boundary?

Quotes

 * Akihito: "Serves you right." — to Mirai after reuniting with her inside Beyond the Boundary