Shishio Sarari is a Japanese boy living with his parents. He finds Kurobe, a child from the African Pyrimi tribe who stowed away on an airplane to Japan, shivering from cold and hunger within his backyard birdhouse. Mistaking Kurobe for a bird, Shishio offers him bread and a blanket for warmth, establishing their bond.

Grateful for this kindness, Kurobe vows to serve Shishio and initiates a unique repayment ritual. For each favor returned, Kurobe places a stone into a large hole he dug in the yard, continuing this practice until the hole is full, making the ritual a recurring feature of their friendship.

Shishio's home life includes his parents, and his backyard eventually becomes home to Kurobe's younger brother Akabe and Kurobe's unusual pet Pakopako, a miniature two-legged elephant. This space transforms into a miniature replica of the Pyrimi tribe's environment, complete with a tiki representation of their god.

Within the series, Shishio interacts with recurring characters typical of Fujiko Fujio's style: Takane Fujino, his love interest; Tiger, the local bully; and Okara, Tiger's sidekick. Later, Gakku joins as a rival from Kurobe's tribe; fluent in Japanese, Gakku frequently plays mean pranks on the group. Shishio consistently acts as the compassionate human counterpart, facilitating Kurobe's integration into Japanese daily life and comedic situations.