Mayumi Nanba is the mother of Mutta Nanba and Hibito Nanba, the two central brothers of the story. She is a warm and devoted parent, characterized by her loving, caring, and enthusiastic nature. Her primary motivation is the well-being and happiness of her children, and she consistently supports their ambitions, including Mutta’s late-blooming pursuit of becoming an astronaut and Hibito’s career as a JAXA astronaut. Her role in the narrative is that of a supportive family member who provides emotional stability and encouragement, often appearing in moments that highlight the familial bonds that ground the protagonists. Her relationship with Mutta and Hibito is close and nurturing, though she is not a central figure in the astronaut training plotlines. While she does not possess notable professional abilities beyond her role as a mother, her steadfast presence and encouragement are integral to the emotional landscape of the series. Her character does not undergo significant development over the course of the story, remaining a consistent source of warmth and support.