"Perman: Birdman ga Yatte Kita!!" is a two-part anime special based on the popular "Perman" manga by Fujiko F. Fujio. The story revolves around Mitsuo Suwa, a young boy who becomes a superhero named Perman after being chosen by Birdman, an alien from the planet Bird. Birdman grants Mitsuo and three other children—Booby, Pako, and Peko—special powers and gadgets to fight evil and protect Earth. The children must keep their identities secret, as revealing them would result in the loss of their powers.

The special introduces a new antagonist, the mysterious Birdman, who arrives on Earth with unclear intentions. Unlike the original Birdman who granted the Perman team their powers, this new Birdman appears to have a darker agenda. The Perman team must uncover his true motives while navigating the challenges of maintaining their secret identities and balancing their superhero duties with their everyday lives.

Mitsuo, the protagonist, is a kind-hearted but clumsy boy who often struggles with the responsibilities of being a superhero. Booby, his robotic dog companion, provides comic relief and assists in missions. Pako, a strong and athletic boy, and Peko, a clever and resourceful girl, round out the team, each contributing unique skills to their missions. Together, they face various threats, including the enigmatic Birdman, who tests their abilities and resolve.

The narrative explores themes of teamwork, responsibility, and the duality of ordinary life versus superhero duties. The Perman team must rely on their wits, gadgets, and each other to overcome challenges and protect their world. The special maintains a lighthearted tone while incorporating moments of tension and action, staying true to the spirit of the original "Perman" series. The characters' interactions and growth are central to the story, highlighting their camaraderie and determination to do what is right.