High school student Makoto Tsukishima receives a devastating diagnosis: he has only twelve months left to live. Resigned to his fate, he decides to withdraw from those around him to spare them the pain of his inevitable death, giving up on ever confessing his feelings to his crush, Tsubasa Minami. However, his plans are upended when Tsubasa, an energetic and determined girl, unexpectedly invites him to join her film club. The club, which is in need of a male lead who looks exactly like him, provides the perfect excuse for them to grow close as they work together on a movie project.

As Makoto and Tsubasa begin to form a genuine connection, the weight of his secret becomes increasingly unbearable. Torn between his desire to cherish his remaining time with her and his determination to shield her from the truth, Makoto sets a painful plan into motion. The narrative, however, is not solely from his perspective. The story deepens by shifting focus to Tsubasa and the film club president, Aoi, revealing the emotional fallout and the hidden thoughts of those around Makoto as they navigate the divide between the fiction they create on screen and the harsh reality of his illness. The high school film club setting serves as more than just a backdrop, acting as a lens through which the characters explore themes of memory, legacy, and the desire to capture fleeting moments.

The novel is structured to deliver its emotional impact through these multiple viewpoints and a notable time jump, concluding ten years after Makotos second year of high school. This epilogue provides a sobering look at how the characters lives have been shaped by their unforgettable love, exploring how hope can connect the past to the future even in the face of an inevitable tragedy.