Vacation (Onsen 温泉) is the second Accel World OVA.
After winning a Territory Battle against the Blue Legion, Leonids, Arita Haruyuki is due for a physical re-examination in two weeks. If he fails, he'll be unable to participate in Territory Battles. Kurashima Chiyuri spends a week to get him into shape but fails. Kurasaki Fūko then invites the Nega Nebulus for a weekend spa treatment to help Haru. While in the hot spring, Chiyuri and Fuko discuss Haru before he became fat. Meanwhile, Haru finds an old video game and recalls his father helping him play but cannot recall the details leading to his parents' divorce. He is then met by Kuroyukihime in the hot spring, who confesses her subconscious fears of him are becoming physically fit, thereby leaving her and giving up Brain Burst. However, Haru proclaims that he will always remain by her side. Kuroyukihime hugs him out of gratitude, but this leaves him stunned, and he later becomes bedridden because of exhaustion. Nonetheless, Haru later passes the re-examination and joins the Nega Nebulous in their next battle.
- This OVA was bundled with the video game, Accel World: The Peak of Acceleration.