"Her Blue Sky" is a poignant anime film that intertwines themes of family, music, and time travel. Set in the rural town of Chichibu, the story centers on two sisters, Aoi and Akane Aioi, whose lives are deeply affected by the tragic death of their parents in a car accident when they were young. Akane, the older sister, sacrifices her dreams of becoming a musician to raise Aoi, while Aoi, now a high school student, harbors a passion for playing the guitar and idolizes Shinnosuke "Shinno" Kanamuro, a musician who was close to Akane in their youth.

The narrative takes a fantastical turn when Aoi encounters a mysterious young man named Dan, who bears a striking resemblance to Shinno. Dan is revealed to be Shinno from 13 years in the past, having traveled to the present through a supernatural phenomenon tied to a local legend about a bridge. This unexpected reunion stirs unresolved emotions and memories for Akane, who had suppressed her feelings for Shinno after he left town to pursue his music career.

As the story unfolds, the characters grapple with their past choices, unfulfilled dreams, and the complexities of their relationships. Aoi, inspired by Dan's presence and her sister's sacrifices, begins to confront her own aspirations and fears. The film explores the impact of time and loss on personal growth, as well as the enduring bonds of family and the healing power of music.

The central characters are Aoi, a determined and introspective teenager; Akane, a selfless and resilient older sister burdened by her past; and Dan, a charismatic yet conflicted musician caught between two timelines. Their interactions drive the emotional core of the story, blending moments of nostalgia, regret, and hope. The film's narrative structure seamlessly weaves together past and present, creating a layered and heartfelt exploration of love, sacrifice, and the pursuit of dreams.