Sealed away in a volcano for centuries, two massive eruptions took place. One awoken the insectoid monster Kemjila and another awoken Birdon, a large prehistoric bird. After being released, Birdon took off in search of food, which instinctively was Kemjila. It then began attacking nearby buildings in search of food, marking the city as his own territory. Then Birdon noticed a fight between Ultraman Taro and a full-grown Kemjila.

Although Birdon and Kemjila were instinctive rivals and share and predator/prey relation, Birdon saw Ultraman Taro as a threat to his "territory" and attacked him instead, stabbing the Ultra repeatedly all over his body with his sharp beak until he died of his injuries. Two Giant Monsters Close in on Taro! With Taro dead but inedible to the massive bird, Birdon turned his attention back to Kemjila, attempting to escape. Birdon attacked Kemjila and the two monsters resumed their fight, with the giant bird swiftly overpowering the insect before killing it with its beak and proceeding to tear its body to pieces and eat them. Upon finishing, Birdon took off to return to its volcanic nest, leaving the city devastated over Ultraman Taro's death.