Kayo Nakamura is a supporting character in the story of White-Collar Worker Kintaro. She is the mother of a daughter named Masumi and lives in the Tōhoku region, where she opens her home to provide lodging for others. When the protagonist Kintaro Yajima and his young son Ryuta are transferred from Tokyo to a remote branch office as a form of punishment, Kayo Nakamura becomes their landlady, offering them a place to stay in her residence.

Kayo Nakamura plays a crucial role in the domestic and emotional landscape of the narrative, particularly concerning the strained relationship between her daughter and the local branch manager, Yozo Igo. Masumi, having conducted her own investigations, comes to the painful realization that her supposedly deceased father is actually Mr. Igo, the angry and lazy superior under whom Kintaro is forced to work. This revelation positions Kayo Nakamura at the center of a family drama involving long-held secrets, absence, and the difficult prospect of reconciliation. Her home becomes the physical space where the lives of Kintaro, his son, and her own fractured family intersect.

While the character lacks a detailed personal history or explicitly stated internal motivations, her actions demonstrate a quiet strength and a capacity for care. By taking in Kintaro and Ryuta, she provides them with stability and a supportive environment during their time of professional exile. The story also places her in direct physical peril. In the escalating conflict with rival construction interests and corrupt political figures, a mail bomb is sent to her home, and she is injured in the ensuing explosion alongside the young Ryuta. This event underscores her position not merely as a passive background figure but as someone whose safety is directly threatened by the central corporate conspiracy, raising the stakes for Kintaro as he moves to confront those responsible.

Kayo Nakamura's key relationships are defined by her roles as a mother and a caretaker. Her connection to her daughter Masumi is the primary driver of the family mystery surrounding Mr. Igo. Her relationship with Kintaro is one of mutual respect and support, as she provides him a home while he, in turn, becomes entangled in the secrets of her family. The character does not display any notable professional abilities or special skills, as her function in the plot is tied to the themes of family, loyalty, and the personal costs of corporate warfare. She serves as a quiet anchor for the protagonists, representing the ordinary lives that are affected by the larger battles being fought by the reformed delinquent turned salaryman. While her personality is not explored in extensive depth, the narrative consistently casts her as a figure of maternal resilience, enduring hardship and housing the story's heroes within her own domestic sphere.