Tsuneo is a university student and Josee is a young girl who has rarely gone out of the house by herself due to her being unable to walk. The two meet when Tsuneo finds Josee's grandmother taking her out for a morning walk.

One day, I-a high schooler-found a paperback in the hospital. The "Disease Coexistence Journal" was its title. It was a diary that my classmate, Sakura Yamauchi, had written in secret. Inside, it was written that due to her pancreatic...