The Capsules are a teenage biker gang that resided in Neo-Tokyo. Founded, and led by Shotaro Kaneda. The Capsules consists of a loose group of young friends, including Tetsuo Shima, Yamagata and Kaisuke amongst others. The Capsules have a deep rivalry with the Clowns biker gang.
The Capsules are involved in various criminal activities, including drug dealing, vandalism and, due to being a biker gang, reckless driving and endangerment.
We first meet members of the Capsules, Kaneda, Tetsuo and Yamagata, in and around their regular hangout the Harukiya bar. Later joined with Kaisuke, they quickly become embroiled in a battle against The Clowns.
As the battle reaches its climax, Tetsuo is involved in an accident caused by the escaped Esper Takashi. Tetsuo is then taken to the military hospital, having suffered some injuries during the accident. The others are taken into military custody.
After being freed from military custody, the Capsules, as an organization, play little to no further role in the story of Akira. They appear in further scenes in school, and on nights out, but are heard to have largely disbanded at some point after Kaneda becomes involved with the Resistance.