"Jikken-hin Kazoku: Creatures Family Days" centers on a family of artificially created beings known as "Creatures," who were designed to serve as experimental subjects for humanity. The story unfolds in a world where these Creatures, despite their origins, strive to live ordinary lives and understand what it means to be human. The family consists of the father, mother, and their three children, each with unique abilities and traits resulting from their artificial creation. The father, a strong and protective figure, struggles with his role as a provider while grappling with his own identity. The mother, gentle and nurturing, seeks to create a sense of normalcy for her children despite their unconventional existence. The eldest child, a boy, possesses heightened physical abilities but struggles with emotional vulnerability. The middle child, a girl, has the power to manipulate objects with her mind but faces challenges in controlling her abilities. The youngest, a boy, is still discovering his own powers and place within the family.

The narrative explores their daily lives as they navigate societal prejudice, the ethical implications of their creation, and the complexities of family dynamics. The family faces external threats from those who view them as mere experiments, as well as internal conflicts arising from their own insecurities and differences. Throughout the series, themes of identity, belonging, and the meaning of family are examined as the Creatures strive to protect one another and carve out a place for themselves in a world that often rejects them. The story balances moments of tension and action with heartfelt interactions, highlighting the resilience and humanity of the family despite their artificial origins.