Nemu is the oldest of the Haibane residing at Old Home, having hatched from her cocoon approximately nine years before the events of the series. Her name, meaning sleeping, is derived from her cocoon dream, in which she saw herself sleeping. This dream also gives her a perpetually drowsy and sedate disposition; she is often seen napping, even at her job in the town's library, where her employer tolerates her dozing because she performs her work capably. Her personality is calm, patient, and composed, making her a steady and unobtrusive presence among the more energetic residents of Old Home. Nemu's primary motivation appears to be a desire for peace and quiet, as well as a deep sense of loyalty to her fellow Haibane, particularly Reki. She serves as a quiet voice of reason in the group, providing gentle emotional support rather than taking a leadership role. Her role in the story is largely that of a supportive elder figure and a bridge between the past and present of Old Home, as she carries the memory of events that occurred before the arrival of newer members like Rakka. The most significant relationship in her life is her long-standing friendship with Reki. They have known each other since Reki hatched approximately two years after Nemu, and Nemu is the only person who fully understands the depth of Reki's long-term suffering and inner turmoil. She also had a close bond with Kuramori, the former senior Haibane who cared for both her and Reki before Kuramori's Day of Flight. Nemu's development throughout the story is subtle; she does not undergo a dramatic personal crisis but instead fulfills a growing role as a confidante and stabilizer. She eventually prepares for her own Day of Flight, though her narrative remains focused on her unwavering support for Reki during the elder Haibane's final trial. Her notable abilities include her competence as a librarian and her natural talent for being a perceptive and patient listener, which allows her to offer quiet wisdom to those around her.