A plane crashes in the Amazon rainforest, leaving young Amazon (Daisuke Yamamoto) stranded without his parents. Soon adopted by an Incan tribe, Amazon becomes a wild child, living off the land. However, Amazon's idyllic existence is cut short when Gorgos, the Ten Faced Demon, massacres his village, slaughtering everyone except himself in search for the powerful "GiGi Armlet", which gives the bearer fantastic power. Elder Bago, last of the Incas, gives the GiGi Armlet to Amazon for safekeeping while using his knowledge of Incan science and magic to perform a mystical "operation" on Daisuke, transforming him into the powerful "Kamen Rider Amazon" before he died. Arriving at Japan, Amazon battles Geddon without full knowledge of their reason of pursuing him. Befriending the nephew and niece of Professor Kousaka, Amazon learns the nature of the GiGi Armlet as he defeats Geddon and then the Garanda Empire.