One morning, Wataru Hoshino found a sleeping girl—in nothing but her underwear—in his room. When she woke up, she quickly escaped by jumping out of the window, but not without punching Wataru in the face first. This girl, Rinna Sawaki, ends up being a transfer student of Wataru's school, as well as the new roommate of Wataru's dormitory. Wataru lives with four other girls and their school teacher, but due to Temizugawa Heavy Industry's cancellation of their aviation branch—South Sakojima Island's major company—the families involved with the corporation have to be evacuated in one year. As a result of this, the four girls have to leave the island in one year's time. Knowing this, Rinna refuses to become friends with Wataru and the other girls, because of the pain that she might experience as a result of their eventual separation; however, Wataru disagrees with her, and over the course of the year, tries to convince her otherwise. (Source: ANN)

Urey is a boy who lives in a laboratory in a lake with an old man. One day they find a strange star in the Little Dipper. The stars are disappearing and the Little Dipper changes into a fish shape. To save stars, they begin to sail across the Milky Way to the place where the strange fish lives.

Noya Itsuki just transferred to Ebisugawa High School. Since he has always had a fascination with space, he decides to join the Astronomy Club. However, he mistakenly walks into the Asstronomy Club - a club whose members are all female otaku. Itsuki notices that the members are really weird, but he has yet to realize that he joined the wrong club. His life becomes very strange very quickly.

Spin-off of Accel World included on the anime Blu-ray/DVDs.