Yuuichi-kun died. A boy so kind, jumping off a railway bridge? That’s impossible, it just can't be true. "I'm sorry, I couldn't do anything. Even though I knew, that Yuuichi-kun would pass away." "Huh?" "Because I can see it, you know." Chisuzu, a high school classmate, says this, confessing that she "knew" about Yuuichi's final moments. Mitsufumi, Yuuichi's remaining best friend, begins to trace the mystery of his friend's death alongside this mysterious girl. ——And then, the two of them learn of another "ending." That Chisuzu will die one year from now.