Machi Kuga is a supporting character in the anime and manga series A Galaxy Next Door. She is the younger sister of Ichiro Kuga and the older sister of Fumio Kuga, making her the middle child of the three siblings. Machi is a third-grade elementary school student, approximately nine years old, living with her brothers in the apartment complex inherited by Ichiro after the death of their father.

Machi has a bright and cheerful personality, often described as the mood maker of the Kuga household. She is naturally sociable and friendly, which makes her easy to get along with. Despite her young age, Machi possesses a strong sense of responsibility and maturity. She frequently takes care of her younger brother Fumio, allowing Ichiro to focus on his demanding job as a shoujo manga artist. She is deeply compassionate and caring, especially toward Ichiro, and she worries about him when he overworks himself. However, she also has a sensitive side, showing that her cheerful exterior sometimes masks her own concerns for her family's well-being. Her primary motivation is to support her older brother and help maintain a stable, happy home life without adding to his burdens. She actively tries not to worry or trouble Ichiro, demonstrating a maturity beyond her years.

Machi has a strong interest in fortune-telling and often invents her own original methods using sticks, cards, or other items. She frequently performs these fortunes on Ichiro, playfully observing how his relationships and daily life unfold. She is also keenly aware of the budding romance between Ichiro and Shiori Goshiki, watching their interactions with interest.

In the story, Machi's role is that of a supportive and grounding presence within the Kuga family. She helps manage household duties and childcare, which provides a stable environment for the narrative to unfold. Her key relationships are with her older brother Ichiro, whom she looks up to and cares for deeply, and her younger brother Fumio, whom she often looks after. She also develops a warm relationship with Shiori as she becomes a regular part of their lives. Throughout the series, Machi does not undergo a dramatic personal transformation; rather, her steady, caring nature remains a constant source of stability, and her growth is shown through her increasing comfort with the new family dynamics that develop around her. She does not possess any supernatural or combat abilities, as her notable traits are her practical household skills, her emotional intelligence, and her talent for homemade fortune-telling.