Reverberation (Zankyō 残響) is the first Accel World OVA.
Inside the Umesato Junior School Network Local Network, two girls are trapped and attacked by a mysterious avatar who strips them of their clothes and items. The following day, Haruyuki seems to be distressing Kuroyukihime since he always treats her as his superior and not an equal. After learning from Yuniko that the same phenomena are occurring at other schools, Kuroyukihime assembles the members of Nega Nebulus and together they come with a plan to lure the perpetrator, with Kuroyukihime and Chiyuri acting as baits while Takumu and Haruyuki watch over them in hiding. The plan works and the culprit, who is revealed as a girl named Dushka appears, but while confronting her, she draws the four to a special isolated low-gravity field called Accel Assault. Dushka then activates a new Assault Link command which transforms her into a new avatar and begins attacking the group. Kuroyukihime deduces that the place a branched part of the Accelerated World and activated the Burst Link command followed by the others, transforming themselves into hybrids of their Local Network and Brain Burst avatars. While Chiyuri fights Dushka alongside Takumu, Haruyuki utilizes Incarnation and transforms himself into wings for Kuroyukihime to use together they defeat Dushka. Later, back in the real world, while thinking about their battle, Haruyuki apologizes to Kuroyukihime for the way he acts around her and resolves to get the courage to be more frank with her.
- This OVA was bundled with the video game, Accel World: Awakening of the Silver Wings.