毫不起眼的平凡高中生【我】,某天在醫院撿到了名為「共病文庫」的手寫筆記本。裡面是一名罹患胰臟疾病而餘命無幾的患者,決心與病魔共存而寫下的日記。但令【我】意外的是,這本日記的作者竟是【我】的同班同學,班上人人喜愛的女生.山內櫻良。【我】成為除了櫻良的家人之外,唯一知道她有胰臟病的人。原本毫無交集的兩人,就這樣展開一段奇妙的交流……
In this deeply moving first-person story, an introverted high school boy finds his classmate’s diary – and learns her biggest secret. Yamauchi Sakura is dying from a pancreatic disease and now he is the only one person outside her family to know the truth. The last thing the boy wants is to be her friend, but Sakura’s cheerful demeanor and their shared secret draw them together in this heartrending tale of friendship and mortality.