Billy Inu is a member of the "Ken-zoku," a dog-like species capable of flight that migrated to the human world. This species uniquely understands both human language and canine communication. He resides with the Amemori family, specifically alongside Tetsuo and Tatsuo, and shares the household with another Ken-zoku companion named Gari Inu. His presence in the Amemori home and neighborhood sparks comedic situations involving misunderstandings and unexpected events, often extending to interactions with local dogs and involving Dr. Torino, who develops human-powered aircraft. Billy Inu's activities drive chaotic and humorous incidents that define the narrative, consistently centering on lighthearted neighborhood occurrences.