Elder Bago serves as a pivotal figure in the origin of the protagonist, appearing in the first episode of the series. He is the chief of an Incan tribe that secretly lived deep within the Amazon rainforest, preserving the ancient knowledge and traditions of their civilization far from the outside world.

Bago is defined by his profound responsibility and selflessness in the face of tragedy. His personality reflects the wisdom of a tribal elder and the desperation of a guardian who has witnessed the destruction of everything he was sworn to protect. When the ten-faced demon Gorgos attacks the village to obtain the secrets of the Inca, including the powerful GiGi Armlet, Bago is mortally wounded. Despite his critical injuries, his primary motivation is not survival but ensuring that the armlet does not fall into evil hands. To achieve this, he makes a split-second decision to entrust the fate of the artifact and his people's legacy to a young orphan named Daisuke Yamamoto, who had been adopted by the tribe.

Bago's role in the story is that of a creator and mentor, though his mentorship is delivered posthumously through his final actions. With his last breath, he performs a mystical operation on Daisuke using a combination of advanced Incan science, tools, and medicines to modify the boy's body. This procedure transforms Daisuke into the powerful warrior known as Kamen Rider Amazon. Immediately following the operation, Bago bestows the GiGi Armlet upon the newly transformed hero. His final instruction to Daisuke is to travel to Japan and seek out Professor Taro Kosaka, a scientist who possesses further knowledge regarding the armlet.

Key relationships defining Elder Bago are his bond with Daisuke Yamamoto and his opposition to Gorgos. He acts as a surrogate guardian willing to sacrifice his life to save Daisuke and gift him the power to fight. Gorgos stands as his mortal enemy, the force that annihilated his family and tribe, driving the events of the narrative. Regarding character development, Bago remains a static figure, as his death occurs almost immediately after the inciting incident. However, his decision and sacrifice are the emotional catalyst that propels the hero on his journey.

In terms of notable abilities, Elder Bago possesses no physical combat prowess relevant to the battles that follow, but his expertise lies in ancient Incan science and magic. He is skilled enough to perform a complex biological transformation on a human subject using rudimentary tools, effectively creating a super-soldier to carry on his fight. This knowledge of the GiGi Armlet and its operation constitutes his greatest power and his legacy.