Naoto Tamura, a new detective in Central City, is killed by a Bionoid Monster in the line of duty. Doctor Kenzo Igarashi, a man whose experiments had been responsible for the Bioron syndicate's existence, brought the man back to life as a cyborg detective, Jiban.

Bounty hunters Iria and Bob travel to Earth to capture an escaped bio-engineered fighting machine called Zeiramu.