The Bugster virus - a new type of virus that slowly takes over its host, before converting them fully into a virtual creature known as a Bugster. The only form of combat against this viral threat are the Kamen Riders of the Computer Rescue Center, a secretive medical team working for the Ministry of Health. Enter Emu Houjou, a pediatrics intern and a genius gamer, who stumbles into the fight against the Bugsters as Kamen Rider Ex-Aid!