In a world where humans can have their wish granted via the Goddess Help Hotline, a human, Keiichi Morisato, summons the Goddess Belldandy by accident and jokes that she should stay with him forever. Unfortunately for him, his "wish" is granted. Suddenly, Keiichi is now living with this gorgeous woman all alone, causing him to be kicked out of the all-male dormitory he was staying in. But soon, after they find lodging in a Buddhist temple, Keiichi and Belldandy's relationship begins to blossom. Although they are both awkward and rather uncomfortable with one another at first, what awaits these two strangers could turn out to be an unexpected romance. [Written by MAL Rewrite]

In the series' backstory, 102,000 years ago in a place that would be modern-day Mexico, it started with a mysterious but powerful race with incredibly long lifespans and the ability to absorb life forces from plants and animals, although they had the disadvantage of being easily disintegrated if exposed to sunlight and thus lived underground instead. Kars, an underground-dwelling humanoid being known as a Pillar Man, created a stone mask which grants immortality by absorbing life energy to conquer the sun (which kills his kind). However, the stone mask cannot penetrate his head and unlock Kars' true potential. As he tirelessly slaughtered things for blood to activate the stone mask, his tribe begins to fear Kars for his obsession. When his tribe says Kars must be killed, Kars is angered and questions them if they want to conquer the sun. If they objected, Kars would say they will die. As his tribe attempts to kill him, Kars and his companion Esidisi fight back. He slaughtered all but four of the tribe.

The moment of reckoning has arrived as the illustrious Football Frontier International is finally underway. After winning the national Football Frontier, the newly assembled Raimon Junior High School soccer team awaits the announcement of Inazuma Japan—the team of players who will represent Japan at the international tournament. Asuto Inamori, along with the "Demon of the Field" Ryouhei Haizaki and the "Emperor of the Pitch" Yuuma Nosaka, quickly realize that they are up against forces far greater and more powerful than they anticipated. In Inazuma Eleven: Orion no Kokuin, mysterious powers are at play within the tournament that threatens to alter the course of history and the game of soccer itself. With the help of their cunning coach Zhao Jinyun and the inexplicable newcomer Ichihoshi Mitsuru, Inazuma Japan must defend the world of soccer in their most difficult challenge yet. [Written by MAL Rewrite]

The OVA will be bundled with the 7th volume of the manga, scheduled to ship on August 26, 2015. It will be a sea bathing episode. (Source: MAL News)