Sawako, a schoolteacher in a Shikotan Island village under postwar Soviet occupation, partners with Tatsuo—father of protagonists Junpei and Kanta—to covertly distribute emergency food supplies to struggling villagers. Their clandestine efforts unravel when Soviet authorities arrest Tatsuo, escalating risks for the community. After Japanese residents are forcibly relocated to internment camps, she joins Tatsuo’s sons and their uncle Hideo on a treacherous quest to find him, her unexpected participation startling Hideo and underscoring her resolve. When Soviet soldiers pursue the group, she prioritizes the children’s escape, fleeing with them as Hideo diverts the threat.

Her bond with the brothers transcends her role as an educator, evolving into a maternal guardianship after their mother’s death. Fleeting narrative hints allude to quiet, unvoiced affection for Tatsuo, though the story’s focus on the children leaves these emotions unexamined. Decades later, she returns to Shikotan with an adult Junpei, honoring the memories of Tatsuo and Kanta. Attending a graduation ceremony for those deprived of formal rites due to wartime upheaval, she reaffirms her ties to the community. The narrative closes with her joining a symbolic gathering of Japanese and Russian descendants, bridging generations through shared commemoration of their intertwined histories.