A quiet and solitary high school student, Haruki Shiga, prefers the company of books over his classmates. His life takes an unexpected turn when he visits a hospital for a routine procedure and finds a handwritten journal in the waiting area. The journal, titled Living with Dying, belongs to Sakura Yamauchi, a vibrant and popular girl in his class. The pages reveal a shocking secret she has hidden from everyone: she is suffering from a terminal pancreatic illness and has only a short time left to live.

When Sakura realizes Haruki has read her private thoughts, she is not angry but rather intrigued by his calm, unemotional reaction. Unlike her family and close friends, he does not treat her with pity or awkwardness. She playfully enlists him as her confidant, and the two most unlikely people form a unique bond. As the story unfolds, Haruki is gradually pulled out of his shell, accompanying Sakura on a series of small adventures to help her fulfill a bucket list of experiences, including a spontaneous trip to Fukuoka where they explore the city and share meals. Through their time together, Sakura encourages Haruki to connect with others, while he provides her with a sense of normalcy away from the weight of her illness. Despite their growing closeness, Sakura insists that their relationship is not romantic, adding a layer of unspoken depth to their connection.

The narrative takes a devastating and abrupt turn that defies expectations. Before her illness can claim her, Sakura is murdered, the victim of a random killer in a senseless alleyway attack. Haruki is shattered by the sudden, meaningless loss, a stark contrast to the meaningful battle he had been preparing to witness. Overwhelmed by grief, he refuses to attend her funeral. Eventually, he finds the strength to visit her home, where her parents give him Sakura’s journal as she had wished. Reading her final words, he discovers the true depth of her feelings for him and her desire for him to live a full life.

In the aftermath, a significant narrative arc follows Haruki as he processes his grief by reaching out to Sakura’s best friend, Kyoko, who was unaware of the terminal illness. He shares the contents of Living with Dying, including Sakura’s final message to her. Through this painful conversation, he confesses his own love for Sakura, which he had never fully expressed. The story resolves not with a romance fulfilled, but with Haruki accepting her death and vowing to live by the lessons she taught him—to open his heart and truly engage with the world, carrying her memory with him as he moves forward.