In the rural countryside of Kochi Prefecture, Japan, Mrs. Naito cherished her family and nurtured a close bond with her daughter Suzu through shared music. She actively encouraged Suzu's early passion for singing and composition, frequently practicing alongside her. Mrs. Naito had brown hair and brown eyes, often wearing a beige striped shirt with white stripes.

During a severe downpour when Suzu was in first grade, Mrs. Naito spotted a child stranded on an isolated island amid flooding. She attempted a rescue, successfully saving the child but drowning in the process. The incident occurred before Suzu's eyes, inflicting profound emotional trauma. Some villagers later criticized Mrs. Naito's decision to prioritize a stranger's child over her own safety.

Beyond her family, Mrs. Naito maintained social ties as a dedicated member of a local choir, practicing regularly and earning their regard as a good friend. After her death, the choir preserved a group photo featuring her and pledged to support Suzu in her memory.

Her death deeply affected Suzu, who interpreted the sacrifice as abandonment and harbored lasting resentment. This contributed to Suzu losing her singing voice, withdrawing socially, and growing distant from her father. The choir members remained a presence in Suzu's life, serving as a connection to her mother.