Mai, an elementary school student, serves as the primary caregiver for her nonverbal older brother Dai-chan, whose physical impairments and toddler-level cognition render him fully dependent on her. Though biologically younger, she shoulders responsibilities like carrying him, managing his daily needs, and assisting him during homework sessions—tasks that sometimes strain her patience amid her own school obligations.

A turning point arises when her class participates in an exchange program with a school for disabled children. After classmates cruelly mock Dai-chan, sketching a caricature of him on the blackboard, Mai grapples with humiliation and anger, torn between defending her brother and fearing social rejection. This conflict intensifies when her mother’s sudden illness jeopardizes Dai-chan’s care, risking his relocation to a specialized orphanage. Resolute, Mai fights to keep him home, determined to preserve their bond despite institutional pressures.

Her perspective on disability evolves through harsh peer ridicule and her tentative friendship with a wheelchair-using girl from Dai-chan’s school, who painstakingly communicates through writing. This connection challenges Mai to see disability as multifaceted, extending beyond her brother’s limitations. Meanwhile, her family’s strained dynamics—an overworked father and an overwhelmed mother—highlight the relentless demands of caregiving, mirroring broader societal struggles.

As external judgments clash with her deepening empathy, Mai’s initial embarrassment transforms into steadfast advocacy. She prioritizes Dai-chan’s comfort over others’ opinions, channeling her frustration into proactive efforts to safeguard their fractured yet resilient family unit.