Two years ago, a mysterious wind swept over the Earth without warning, taking everyone's memories with it. Not knowing their names or even how to speak, cars crashed, planes dropped from the sky, and society crumbled in an instant. One young man happens to wander into a military testing facility, where he meets Johnny, a young boy who underwent experimental memory enhancement treatment and could, therefore, still remember who he was. Johnny names the young man Wataru and teaches him everything that he can before his frail body fails him. Wataru sets out on a journey to see if he can find other people like him, and in San Francisco, he meets a mysterious silver-haired woman named Sophia, who refuses to speak about her past. Sophia says that she is heading to New York, and decides to travel together with Wataru. As the pair make their way across America, they learn about what has happened to the rest of society, and what the essence of humanity really is.

OVA bundled with the Accel World simulation and action games. The Blu-ray OVA discs came with the PS3 limited edition versions and the DVD with the PSP limited edition versions. The project was split into two PSP and PS3 titles, and one episode was released with each game: #EX01: Reverberation;Zankyou (bundled with Stage:01 Ginyoku no Kakusei) #EX02: Vacation;Onsen (bundled with Stage:02 Kasoku no Chouten)

Japan is secretly controlled by a tyrannical group of ninjas called the Shinogara. Their finest assassin is a man named Hayate Kanuma, whose father leads the Shinogara. Hayate, however, knows that the secret society's control over Japan is wrong. Sacrificing his own safety, Hayate kills his father. Now he's on the run, safe almost nowhere from his vengeful former comrades except perhaps for the one hiding place he decides upon: his sister. After possibly being fatally wounded, Hayate is able to transfer his soul into his sister's body, temporarily sharing it with her. His sister, Shiori, can awaken Hayate and call upon his ninja abilities when the Shinogara are close at hand but each time she does so, a little more of her true self is lost. This arrangement can't possibly go on forever, so how will Hayate finally defeat the Shinogara?

Recap of the first 24 episodes of .