Kyoukai Senjou no Horizon is composed of twenty-six episodes split into two broadcast schedules, with the first thirteen episodes released from October 2 to December 25, 2011. The series continued into its second season, entitled Kyoukai Senjou no Horizon II, on July 2012.
Kyoukai Senjou no Horizon chronicles the story of a futuristic civilization which returned to Earth after constant warfare hindered them from traveling beyond the post-Apocalyptic Earth. At this stage, a small archipelago called the Divine States were the only hospitable land on Earth, and in order to regain the techonology they lost over many years of war, they decided to recreate history on this Divine States, with a book called Testament as basis.
It is the year 1648 in the Testament Era. Toori Aoi faces the tenth year anniversary of the death of Horizon Ariadust in an accident. As he prepares to celebrate the occasion by proposing to P-01s, an automaton who looks exactly like his long-departed friend, he discovers that his suspicions on P-01s' appearance actually has a basis, as P-01s is in fact Horizon Ariadust, reborn in a robotic body. In addition to this, Horizon's memories are now stored in eight powerful weapons called the Mortal Sin Armaments, which are now in the possession of key people in established countries in the Divine States.
To retrieve the memories of Horizon Ariadust, Toori Aoi, along with his friends and allies, begins a crusade against different obstacles as key events in history are retold in a futuristic manner.
After the first Mortal Sin Armament, the Lype Katathlipse, was retrieved by Toori and P-01s, they travel to England, where they would be caught in a historical recreation of a key event in the Anglo-Spanish War. The representatives of Spain, Tres España, and England split Toori and his friends into the two sides of the war. As the two sides clash, a darker side of the Testament is revealed as an innocent is sentenced to die under the orders of the Testament.
Tenzou Crossunite, one of Toori's allies, decides to deny the Testament by saving the girl from its undeserved death, while England's Mortal Sin Armament becomes a valuable target as well.
- Episode 01: Those Lined Up Before the Horizon
- Episode 02: Innocents at the Table
- Episode 03: Commandos in Town
- Episode 04: Covert Ops Under the Night Sky
- Episode 05: Graduates Under the Moon
- Episode 06: Advocate at the Confession Grounds
- Episode 07: Musashi's Knights
- Episode 08: Ruler of the Land
- Episode 09: The Summit's Flower
- Episode 10: The Trumpeter at the Start Line
- Episode 11: Musashi's Mr. Impossible
- Episode 12: Opposition Against Crossing Over the Parallel Lines
- Episode 13: Those Lined Up Above the Horizon
The opening theme song of the first season is entitled "Terminated", sung by Minori Chihara, who also voices P-01s in the anime series. Meanwhile, the series has two closing theme songs, dubbed as "Side Horizon" and "Side Ariadust". The "Side Horizon" closing theme song is "Stardust Melodia", sung by Ceui, while the "Side Ariadust" one is "Pieces", performed by Airi.
For the second season, the opening theme is entitled "ZONE / / ALONE", also sung by Minori Chihara. There are two closing theme songs following the format of the first season. This time, however, the songs are dubbed "Side SunRise" and "Side SunSet". The "Side SunRise" closing theme song is "Sora no Uta" by Masami Okui, and the "Side SunSet" one is "Kanashimi wa Dare no Negai Demo Nai" by Aira Yuki.
- Anime Series Official Website (Japanese)