"I shall wait for you at the edge of the Abyss..." That is what a mysterious man said to Sora Mukujima in one of his dreams. Sora lived a modest life together with his parents, until one day, that peaceful life fell apart. A massive tower appeared. His brother, a soldier, was unreachable. And monsters began to attack suddenly. When he was in a desperate situation, the man from his dream appeared before him. And when he woke up next, he was in an unfamiliar place. It was a different world called the "Abyss", just as the man had called it in his dream. In order to return to his original world and save his family, Sora vows to challenge the Abyss, fight, and grow stronger at all costs!