Christine is a ten-year-old Chinese-Taiwanese American girl who is reserved and studious. She is deeply concerned with meeting her parents' high expectations. She plays the violin and attends Chinese lessons taught by her mother. Her quiet, cautious nature is challenged when she meets her confident new neighbor, pushing her to explore her own interests like popular music and dancing.

Moon is an energetic, confident girl who moves into the spare unit of the Hong family's home. She has a zest for life, loves the edgy K-pop artist Chara, and is raised in a vegetarian, Buddhist household by her single mother. Despite her cheerful exterior, she struggles with feelings of isolation and harbors a private belief that she truly belongs among the stars.

Mrs. Hong is Christine and Vivian's Chinese mother. She maintains a strict household with rigid expectations for her children's behavior and performance. She actively participates in her community, teaching Chinese language lessons to neighborhood children from her home.

Mr. Hong is Christine and Vivian's Taiwanese father. He shares his wife's traditional values and worries about outside influences on his daughters. He provides for his family and connects with them through cultural traditions, such as sharing traditional Taiwanese shaved ice.

Vivian is Christine's younger sister. She looks up to her older sibling and reacts strongly to the social pressures of elementary school. She occasionally relies on her family and friends for protection when facing unkind peers in class.

Mrs. Lin is Moon's single mother. She runs a local plant nursery where she is known to sing to her plants. She is a warm, friendly Buddhist who prepares traditional vegetarian meals for her neighbors and fosters a loving, free-spirited environment for her daughter.

Madison is an outgoing, wealthy classmate of Christine and Moon. She has short blonde hair, frequently discusses her family's travels, and hosts social events that gather the local kids together for birthdays and parties.

Mr. Pennypacker is an elementary school teacher. He earns the immediate admiration of his new student, Moon, and organizes educational field trips to the local planetarium for his class.