Tomoko Kitabatake is a young Japanese girl residing with relatives in post-World War II Hokkaido. Struck mute by witnessing a traumatic war event, her inability to speak profoundly affects her communication. Feeling like an unwanted burden, she repeatedly runs away from her relatives' home.

During one flight, she discovers Inlen, an escaped Chinese laborer concealed in the nearby forest. Their connection sparks when Tomoko hears him singing a Chinese lullaby. Despite the language barrier and her muteness, they forge a bond through shared emotions and wordless understanding, centered on homesickness and personal tragedy. The lullaby becomes a key emotional touchstone between them.

Separated from her immediate family due to wartime upheaval, Tomoko grapples with intense isolation and a yearning for belonging. Her interactions with Inlen offer mutual emotional support, providing solace amid their distinct struggles. Her character illustrates war's impact on children, emphasizing psychological trauma and the universal need for human connection transcending cultural or linguistic divides.

Her relationship with Inlen develops as a surrogate parent-child dynamic, granting temporary respite from their loneliness. Tomoko's experiences highlight innocence amid historical tragedy and empathy's capacity to bridge profound differences.