Nao Morisawa is a high school student who appears as a central figure in the story of Refrain Blue. Her background is defined by profound loss: one year before the events of the series, she traveled to the same seaside location with her fiancé, who later died in a plane crash. Grief-stricken and unable to move past the tragedy, she attempts to drown herself during a summer trip with her classmates. She is rescued by Matsunaga Yoshihiro, the chaperone of the group, an encounter that becomes the catalyst for her emotional journey.

Nao is portrayed as both intelligent and attractive, but her personality is overshadowed by deep sorrow and a sense of hopelessness. Her initial motivation is to end her own suffering, but as she interacts with Yoshihiro, her motivations shift toward seeking understanding and the possibility of healing. She carries the weight of survivor’s guilt and nostalgia for a future that was taken from her. Her role in the story is that of a grieving young woman whose path intersects with another person carrying a painful past—together, they confront their shared experiences of loss.

Key relationships shape her development. Her bond with Yoshihiro is built on mutual recognition of pain; he becomes not only her rescuer but also a companion in navigating grief. The mysterious girl known as Umi Warabe also influences her, serving as an enigmatic presence that encourages reflection and closure. Through these connections, Nao gradually moves from isolation to a tentative openness, allowing herself to consider the possibility of moving forward.

Nao does not possess any supernatural or extraordinary abilities. Her significance lies in her emotional depth and the quiet resilience that emerges as she learns to face her memories. Her development is marked by a slow, painful process of acceptance, culminating in a renewed sense of hope. The story ultimately shows her transformation from a figure defined by despair to one who can begin to rebuild her life.