Manami is a 10-year-old Japanese-American girl whose life is upended when her family is forced into the Manzanar concentration camp during World War II. Traumatized by the sudden removal from her home and the forced separation from her beloved dog, she loses her ability to speak. To cope with her overwhelming emotions, she relies on drawing on paper and her deep bonds with her family members.

Manami’s elderly grandfather is a widower who lives with his daughter’s family. He finds profound solace in the ocean and in the family dog, Yujiin, whom he rescued after his wife’s death. The harsh desert conditions and personal losses at Manzanar initially plunge him into a severe depression, causing him to withdraw from daily camp life.

Manami's mother is a hardworking and sensitive woman who strives to maintain normalcy for her family amid their unjust incarceration. Though prone to crying when overwhelmed by their circumstances, she quickly organizes their cramped barracks and plants a small garden in the desert dirt to provide fresh food and a sense of routine.

Manami's father is a former fisherman who works tirelessly on the camp's building crews to improve living conditions for his community. He holds traditional views on family roles and expects his children to prioritize their education to secure an easier future. Despite his stern demeanor and long work hours, he shows deep affection for his family through his actions.

Manami's older brother is a college student who gives up his studies in Indiana to join his incarcerated family in California. He takes a job teaching the older middle-school students at the camp and uses his own money to buy them baseball equipment. His strong sense of duty to his community frequently puts him at odds with his father's expectations for his individual success.

The camp warden is an authoritarian figure who oversees the Manzanar concentration camp. He is harsh and demanding, showing little understanding of the prisoners' trauma, and frequently targets those who do not comply with his strict displays of patriotism and order.

Miss Rosalie is a young, kind-hearted teacher who lives in the workers' quarters at Manzanar. Unlike the camp's administration, she treats the Japanese-American children with genuine warmth and respect. She builds a special bond with Manami, encouraging her to express herself through drawing when she is unable to speak aloud.

Kimmi is Manami's 10-year-old best friend whose family is also incarcerated at Manzanar. Cheerful and relentlessly optimistic, she serves as a bright contrast to Manami's withdrawn state. Kimmi continually reaches out to Manami, defending her from bullies and trying to keep her engaged with the other children in the camp.

Keiko is Manami's older sister who avoids incarceration at Manzanar by remaining at college in the Midwest. She serves as the family's primary link to the outside world, sending letters to the camp and encouraging her siblings to pursue their education and freedom.

Yujiin is the Tanakas' beloved pet dog, originally rescued by Grandfather from the beach. When the family is forced to leave for the concentration camp, they are barred from taking him along, and the traumatic separation leaves a lasting impact on the family.

Seal is a small white stray dog adopted by the Tanaka family at Manzanar. Though Manami is initially hesitant to embrace him out of loyalty to Yujiin, taking care of Seal eventually provides her with a renewed sense of purpose and comfort during the harsh winter.

Mrs. Brown is Manami's teacher on Bainbridge Island. She is deeply saddened when she has to inform her Japanese-American students that it will be their last day of school due to the government's removal orders, promising to pray for them.

Mrs. Soto is a pregnant woman whose family is initially assigned to share a cramped barracks room with the Tanakas. The shock of the camp's poor conditions and lack of privacy causes her great distress upon arrival.