The Hoshino family, extraterrestrials planning to invade Earth, find their schemes consistently thwarted by an unexplained aversion to Ojarumaru. This fear triggers visible anxiety and excessive nervous sweating whenever they encounter him. Their invasion attempts repeatedly fail due to their own inherent clumsiness and Ojarumaru's accidental interference.

Hoshino Papa, the patriarch, habitually mispronounces Ojarumaru's name as "Ojamaru," a recurring error during their plots. The family operates collectively, with no distinct personalities or defined roles detailed for members beyond the father. Their narrative function remains fixed as comedic antagonists whose grandiose ambitions are perpetually undermined by their ineptitude and involuntary physiological reactions to Ojarumaru.

Their objectives, relationships, and backstory show no significant evolution across any series, movies, or specials. Their background lacks details about their home planet, societal structure, or motivations beyond the general desire for conquest. Appearances primarily serve episodic comedic purposes, focusing on failed antagonistic plots and their peculiar reaction to the protagonist.

The family maintains a static role throughout the narrative. No documented character development, exploration of their alien society, or resolution to their invasion goals occurs. Their interactions with other characters remain superficial, confined to thwarted schemes and anxious reactions.