In Fujisawa, Kaito Ishikawa brings to life Sakuta Azusagawa, a high school junior who cherishes his days with Mai Sakurajima, Asami Seto, his girlfriend and senior for the past six months. Their quiet rhythm is disrupted when Sakuta encounters Shoko Makinohara, Inori Minase, the girl who has left a lasting impression on him. As he and Mai navigate this strange encounter, they learn there are two versions of Shoko — a middle school girl and an older Shoko who once helped him. The middle school Shoko is revealed to be suffering from a serious heart condition that urgently requires a transplant to save her life.
Sakuta and Mai grow deeply invested in the middle school Shoko’s fate, and Sakuta uncovers a chilling link between his own injuries and the existence of adult Shoko. The adult Shoko has traveled from the future after a successful heart transplant, and her donor was Sakuta himself, who had been declared brain dead after a near-fatal Christmas Eve car accident. Yet Shoko’s feelings for Sakuta in their youth propelled her to return to the past to save him. Against Mai’s wishes, Sakuta makes a grim choice: he decides to sacrifice himself so that Shoko can live.
The plan takes a heartbreaking turn when Mai, acting in a split-second reversal of fate, pushes Sakuta away and is struck by the car herself. The crash alters the chain of causality so that Sakuta survives, but Mai dies and becomes Shoko’s heart donor instead. The shock of Mai’s death leaves Sakuta reeling, while adult Shoko tries to help him cope and even offers one final option: with her aid, they could travel back to rewrite history and avert the tragedy entirely. The ultimate implication is stark — the adult Shoko would disappear if they attempted such a reset.
Sakuta wrestles with an impossible choice, yet he and Mai refuse to give up on Shoko. They resolve to find a way to keep Shoko alive without losing everything they already hold dear. To begin, Sakuta seeks out Tomoe Koga, Nao Toyama, the only person who can see him at that moment, and asks her to summon his past self to the present so they can coordinate. In a race against time, he runs to the site of Mai’s death and tries to push his past self away from the fatal car, but the two versions cannot meet. As the bunny-clad future self fades from sight, the crash is averted, and both Mai and Sakuta survive—but Shoko is left without a heart donor and thus doomed to die.
Refusing to accept this fate, Sakuta and Mai redouble their efforts to save the dying Shoko, knowing that any solution could rewrite everything they have experienced. They press on, and Shoko herself reveals that she now understands the entire sequence of events. She decides to create a future in which she never meets Sakuta or Mai, thereby sparing them the sorrow they have endured. The timeline rewinds to when Shoko was in fourth grade, and she bravely writes down a future where her own existence doesn’t intersect with theirs, effectively choosing to disappear in favor of their happiness.
Time winds forward to New Year’s, returning to the present as Mai has become known for a film inspired by Shoko’s story, a project that achieves success even though she does not remember the precise events. Sakuta and Mai visit a shrine and stroll along a beach, where they first encounter Shoko again, now a healthy young girl. Through the cross-cutting threads of memory and timeline, Sakuta and Shoko gradually recognize one another, and the film’s ending frames a fragile, renewed bond among them, suggesting that love and memory can endure even across the most challenging changes in time.
