Kiku is a 16-year-old Japanese American girl living in Seattle. As a fourth-generation citizen, she initially feels detached from her heritage, unable to read Japanese street signs or speak the language. After mysterious fogs transport her to the 1940s Japanese incarceration camps, she must adapt to life in the barracks while uncovering her family's history.

Kiku's mother is a third-generation Japanese American (Sansei) who raises her daughters in Seattle. She is disconnected from her family's Japanese culture, a result of her own mother's efforts to assimilate entirely after surviving the incarceration camps. She frequently watches political news broadcasts, showing deep anxiety over modern anti-immigrant policies.

Ernestina is Kiku's grandmother, depicted as a young, talented second-generation Japanese American (Nisei) during Kiku's time-travel experiences. She is forced into the Tanforan and Topaz incarceration camps with her immigrant parents. She serves as a musical and historical anchor for Kiku, frequently seen practicing her instrument in the camps.

Aiko is a young, single second-generation Japanese American (Nisei) woman who shares a room with Kiku in the camps. She vigorously protests the unjust treatment of incarcerated citizens and works tirelessly to make their dusty barracks livable. She firmly identifies as American and flatly refuses to teach Kiku the Japanese language.

May is a teenage girl incarcerated in the camps who becomes Kiku's first close friend her own age. Outspoken and determined, she openly complains about the censorship in the camp school. She frequently attends dances with Kiku, sharing a close bond that provides a rare sense of teenage joy.

George is a teenage boy incarcerated at Topaz who critically evaluates the US government's expectations of the Japanese American community. He strongly objects to the idea that incarcerated citizens should swear loyalty and enlist in the military while stripped of their constitutional rights.

Seiji is a teenage boy incarcerated at Topaz who believes Japanese Americans are just as American as white citizens. He feels a strong duty to volunteer for the military, viewing it as a path to prove their loyalty and citizenship.

Mr. Matsuzawa is an older, first-generation Japanese immigrant (Issei) incarcerated at Tanforan. Unable to speak English, he connects with the camp's younger generation by carving intricate wooden gifts, creating tangible links that survive into the present day.

Haruko is a mother trying to care for her two daughters in the harsh conditions of the Topaz Relocation Center. Her husband, a teacher, was arrested shortly after Pearl Harbor, leaving her to manage the family's survival and uncertainty alone.

Sachiko is one of Haruko's daughters, who attends makeshift school classes with Kiku and May at Topaz. She worries constantly about her missing father and entertains the idea of enlisting in the army if it could somehow protect her family.

Emiko is Haruko's daughter and Sachiko's sister. She endures the freezing winter conditions and constant dust storms of the Topaz Relocation Center alongside her family and Kiku.

Miné is an art instructor in the camps who encourages Kiku to sketch their surroundings. She inspires Kiku to document the reality of the barracks, latrines, and guard towers as a vital historical record of their incarceration.

Mariko is Kiku's sister and shares her family's modern-day life. She is disconnected from the Japanese language but helps piece together their grandmother's history by examining surviving artifacts and records.

Mrs. Yamada is a second-generation Japanese American (Nisei) from Berkeley who serves as a teacher for the incarcerated youth. She faces the nearly impossible task of teaching constitutional amendments and civil rights to students whose own rights have been entirely suspended.

James is an older, first-generation Japanese immigrant (Issei) whose fatal shooting by camp guards sparks a massive labor strike. The conflicting rumors surrounding his death galvanize the incarcerated community into demanding a funeral and building a memorial.