While catching fish, Daisuke finds himself at a motocross, frightened by the motorcycles before he saves a man named Tobei Tachibana who was attacked by Kamakiri Beastman. Paying him back, Tobei helps Daisuke overcome his fear of motorcycles to save Masahiko from the Akajuusha before Kamakiri attacks them, with Amazon killing the Beastman. But unnerved why he is hunted by the Geddon, Masahiko learns of Yamamura, one of the members of Kosaka's exploration party into the Amazon. Hoping to find the answer, they and Tobei learn that Yamamura's on the run from Geddon as he holds the secret that Geddon would go to lengths to make silent. When the Beastman Omukade captures Yamamura and his daughter, Daisuke pursues with newly built Jungler, saving them before killing the Beastman Omukade. During the fight, Yamamura is fatally wounded by the Akajusha as Yanamura reveals the "GaGa Armlet", the counterpart of the GiGi, that Gorgos possesses before he died. Daisuke is arrested by the police for attacking an officer when they needed to know his identity in spite of his part in helping them get murderer Oshima. Though he is bailed by Tobei, Daisuke runs off with a hatred for other humans.
The next day, Tobei and Ritsuko find Daisuke as he intends to return to the Amazon. Learning that Masahiko was abducted by Mogura and at Ritsuko's pleas, Daisuke saves his friend and give Mogura a severe beating. Daisuke later finds Mogura being punished for failing Gorgos, saving the Beastman who is shocked. Later, after being told by that Johoku University has gain relics from the Amazon, Daisuke and friends investigate and find the mysterious Quipu which Daisuke could decipher. But the Beastman Yamaarashi arrives and steals the Keep with Daisuke falling into his trap. But with Mogura's aid, Daisuke learns the story behind the GiGi and GaGa Armlets before killing Yamarashi, now knowing Geddon's goals. While searching for Geddon, Daisuke receives a radio from Masahiko so he can know when Gedon's up to no good. After saving a woman from Kani Beastman, Daisuke learns that Mogura is forced by the monster of reveal Ritsuko as a potential weakness. Though he attempts to protect Ritsuko, Daisuke is saddened as she tells him that he's the one Geddon's after and it might be best for everyone if he just goes back where he came from. In spite of this, Amazon saves Ritsuko and friend from Kani and later receives a vest from Ritsuko as her way of thanking him. As Daisuke manages to learn to speak and understand perfect Japanese, he attempts to find Geddon's safe house in order to take the GaGa Armlet from Gorgos.
But he is unaware of the Garanda Empire who offer the Geddon Beastman Hebitonbo a place in their group if he get the GaGa Armlet for them. Hebitonbo enlists Amazon's aid in fight Gorgos before attempting to take the GiGi Armlet as well. But the fight ends with both Hebitonbo and Gorgos dead as the GaGa Armlet then falls into the hands of the ruthless Great Emperor Zero. Learning of Garanda's existence from the Hachi Beastman incident, Amazon fights against the new evil with Mogura's aide before he died helping him against Kinoko Beastman. As Garanda sets up its final plan, the Helium Bomb Operation, Sanshouo Beastman is sent to kidnap the Okmura siblings to hold off Amazon while the plan is completed. However, Amazon manages to defeat Sanshouo before following the Beastman's blood to Garanda's base and braves the traps waiting for him before facing Great Emperor Zero himself. However, Amazon's Gigi Armlet is negated by Zero as he is captured. However, Tobei poses as a Kurojuusha to find Amazon as Zero is about to execute him. But freed when the Gaga Armlet combines with the Gigi Armlet, Amazon becomes immune, as he chases after him before the Garanda leader falls into one of his traps. Destroying the detonation system for the Helium Bomb, Amazon confronts the real Emperor Zero and kills him. With his mission complete, he returns to the amazon forest where he lived because it is his true home, though Tobei believes that he will come back if evil comes to terrorize Japan again.