Amazon's World
Masahiko Okamura
Masahiko Okamura is a 4th grade student whose father died a year prior to Dai-Shocker's arrival, escaping the pain of his father's death by joining the Shocker School that has been established in his world. Because he excels in exposing rebels, Llumu Qhimil uses the boy to find Amazon's hideout. But during the fight, Dai-Shocker's forces turn on him, leading him to take GiGi Armlet from Amazon to get back in Dai-Shocker's good graces. When he is turned in to become the first of Llumu Qhimil's monster conversion project, he realizes that the truth and helps in regaining Amazon's GiGi Armlet and faith in people.
Ritsuko Okamura
Ritsuko Okamura is Masahiko's older sister and is a school nurse at the Shocker School. When she discovers that the Hikari Studio group has infiltrated the school, she sends Shocker Soldiers after them, until Masahiko proves to her that the Kamen Riders are not evil.
Daisuke Yamamoto / Kamen Rider Amazon
Daisuke Yamamoto, known only as "Amazon" is a man from the Amazon Rainforest who traveled across the world to find a place that he could call home, eventually arriving in Japan where he fights Geddon as Kamen Rider Amazon. Though disillusioned after Masahiko used him to get the GiGi Armlet, Amazon regains his trust in humanity when the boy returns the armlet, finding his place by the Okamura. Afterwards, he aids Decade in battle against Apollo Geist and Llumu Qhimil, forcing Apollo Geist into retreat with his Dai Setsudan and destroying Llumu with his Super Dai Setsudan after Decade equipped him with the GaGa Armlet.
Llumu Qhimil
Ten-Faced Demon Llumu Qhimil is the leader of Geddon and Dai-Shocker's designated ruler of this world, developing the mindset that Kamen Riders are the enemies of the human race, rather than Geddon. He has the GaGa Armlet and seeks Amazon's GiGi Armlet to gain their full power and use the unlimited ancient Inca powers to complete his master plan of converting humans into monsters. He normally resembles a torso attached to a large boulder, but he can also assume a humanoid form adorned with the faces of the ten Heisei Kamen Riders from which he can access their powers and counter any of the ten Heisei Kamen Riders attacks. Though he gains the GiGi Armlet, he loses both it and the GaGa Armlet to the Kamen Riders with Amazon destroying him with the Super Big Slice.[ Go-Jaraji-Da In Episode 28, a porcupine Grongi. Destroyed when Amazon used his Jaguar Shock on him. Propheta Cruentus In Episodes 28-29, a Mantis Lord, destroyed by Kuuga Titan Form's Calamity Titan attack. Camponotus Worm Maxilla In Episode 28, a carpenter ant Worm destroyed by Decade's Dimension Kick.
In Episode 28, a cat Makamou. Destroyed when Amazon used his Big Slice on him.
A volunteer military police formed from the residents of the World of Amazon who act in flushing out potential threats. Yobuko In Episode 29, formerly the Vigilantes' leader who gets transformed into a Makamou as a reward by Llumu Qhimil using the powers of both the GiGi and GaGa armlets on him.
Series:  Kamen Rider Decade