The Black Legion members are enjoying a rare opportunity to relax – that is, everyone except for Kuroyukihime. Lately the Black King has become more and more concerned with Haruyuki's unexpected aloofness, and what's worse, she and the gang soon discover that someone in the school network is assaulting students' online avatars and stealing their accessories. Can the Black Legion expose the troublemaker, and will Kuroyukihime be able to resolve her relationship with Haruyuki?
Then, with the help of his friends, Haruyuki must find a way to drop some weight fast or be forced to take the school health improvement program - which means losing his chance to participate in important Accel World territory battles. On Sky Raker's proposal, everyone goes to a special mixed-gender hot spring to help him get healthier, but Kuroyukihime begins to feel uneasy towards Haruyuki getting slimmer...