When friends graduate from junior high school and are enrolled in high school Koichi and Yakko join a motorcycle gang. They make new friends, have fights and flirt with girls. Yakko, however, is not having an easy time of it. Koichi stands up for his friend and joins the yakuza, which brings its own problems with it.
Dormant, experimental cells begin to awaken inside their human hosts, turning them into creatures called 'Amazons'. Two Amazons- Jin Takayama and Haruka Mizusawa- transform into Kamen Riders Amazon Alpha and Amazon Omega, aiming to exterminate the growing threat.
