Mitsi is an eleven-year-old Japanese American fifth-grader living in Seattle when the attack on Pearl Harbor disrupts her life. She is an observant, artistic girl who deeply loves her dog, Dash. As her community faces rising anti-Japanese discrimination and eventual forced displacement to concentration camps, she struggles to adapt to her harsh new reality. She possesses strong principles and empathy, refusing to sink to the level of the bullies who target her.

Mrs. Bowker is an older widow and a dependable neighbor in Seattle. Having carried regret since World War I for failing to stand up for a German couple, she actively refuses to participate in the anti-Japanese racism spreading through the city. She steps in to care for Dash when Mitsi is forced into the concentration camps, becoming a vital source of connection for the young girl.

Ted is Mitsi's older brother, a playful boy who loves performing magic tricks and holds a paper route in Seattle before the war. After the family is forced into the concentration camps, he adapts more quickly than Mitsi but begins associating with a rougher crowd. His changing behavior creates tension between the siblings as he gets caught up in minor thefts.

Debbie is an energetic, observant girl who becomes Mitsi's closest friend inside the concentration camps. She is an avid reader and a ballerina who randomly practices pliés and invents games to pass the time. Beneath her playful exterior, she carries deep anxiety for her father, who was arrested and sent to a separate camp in Montana.

Dash is Mitsi's beloved dog. When the government forbids Japanese Americans from bringing pets into the concentration camps, he stays in Seattle with Mrs. Bowker. His unwavering loyalty and the frequent updates Mitsi receives about his daily activities provide her with crucial emotional stability and a reason to stay hopeful.

Mags is a fifth-grader with curly red hair who has been one of Mitsi's best friends since first grade. Following the attack on Pearl Harbor, she begins distancing herself from Mitsi and aligning with Patty, the class bully. Though she displays passive compliance with the racist atmosphere at school, she secretly wrestles with guilt over the situation.

Judy is a fifth-grade girl with a blond pageboy cut and brown eyes. She is part of the inseparable childhood trio that includes Mitsi and Mags. She quietly succumbs to peer pressure after Pearl Harbor, abandoning her friendship with Mitsi to follow the popular crowd without speaking up.

Patty is a fifth-grade student whose father owns the Atla Theatre. She acts as the primary antagonist at school, actively exhibiting anti-Japanese racism toward Mitsi. She uses her social influence, such as her coveted autograph book and movie invitations, to pull Mags and Judy away from their friendship with Mitsi.

Mom is Mitsi and Ted's mother, who attempts to hold her family together as they face displacement and imprisonment. She encourages Mitsi to try to make the best of their harsh living conditions and maintain her spirit, taking on practical tasks like painting a wooden box for Mitsi's birthday.

Pop is Mitsi's father, who loses his job at the electric company due to anti-Japanese discrimination. He is forced to sell his car to his former boss before the family is displaced. In the camps, he tries to improve their bleak surroundings by building small pieces of furniture from scrap wood.

Obaachan is Mitsi's grandmother, who was born in Okayama, Japan, and moved to America at age sixteen. She frequently wears a kimono and faces humiliating government registration procedures because of her heritage. She spends her time at the concentration camps knitting socks for the Red Cross with other older women.

Lefty, whose real name is Frank, is an older boy at Camp Harmony who quickly becomes a bad influence on Ted. He is a bully and a petty thief who steals from shower robes and targets younger children. His behavior causes constant friction and worry for Mitsi, who fears he is ruining her brother's integrity.

Mr. Hirai is an older Japanese man in the camps who actively brings beauty and utility into the bleak environment. He makes wooden getas (sandals) to help people walk in the camp's deep mud and creates an intricate, calming garden out of rocks and tumbleweeds.

Miss Wyatt is Mitsi's fifth-grade teacher in Seattle. She attempts to maintain a sense of community in her classroom following the Pearl Harbor attack and reads Little House in the Big Woods to her students. Before Mitsi leaves for the camp, Miss Wyatt brings her a drawing pad and colored pencils.

General DeWitt is the military official in charge of the forced displacement of Japanese Americans. Mitsi writes to him directly in a bold attempt to secure permission to bring Dash to the camp, but he initially denies the request on the grounds of wartime sacrifices.

Grace is another Japanese American student in Mitsi's fifth-grade class. Though they share the same ethnic background and impending displacement, Mitsi avoids a close friendship with her because she considers Grace to be bossy and uninterested in books.

Mrs. Tokuda is a young mother in the concentration camp whose husband has been taken away. She cares for a tiny boy named Davy and a baby girl named Donna, often relying on the help of other camp residents, like Mitsi, for babysitting support so she can shower or rest.

Davy is Mrs. Tokuda's tiny, easily distressed son. Mitsi and Debbie frequently babysit him, playing games and drawing pictures to keep him entertained and give his mother a necessary break from the chaos of the camp.

Eddie is an older teenager at the camp who uses his artistic talents to maintain his humor and agency. He draws satirical cartoons of the camp conditions, such as labeling his drawing of the drafty barracks "Air conditioning," proving that creativity acts as a form of resistance.

Miss Pellegrino is a dedicated teacher at Camp Minidoka. Facing a severe lack of resources, she creatively uses butcher paper as a blackboard and starts a library from donated books, giving the displaced children a reason to look forward to school.