The novel tells the story of a man named Hajime, who grew up as an only child in post-war Japan. He forms a deep bond with a girl named Shimamoto during his childhood, but they lose touch as they grow older. Hajime builds a successful life with a wife and two daughters, but he is haunted by his past. When Shimamoto unexpectedly re-enters his life, he is torn between his commitment to his family and his lingering feelings for his childhood love. The novel explores themes of nostalgia, regret, and the complexities of human relationships.

This novel delves into the emotional and physical journey of a heart transplant, beginning with a tragic accident that leaves a young man brain-dead and transitioning to the complex process of organ donation. Through a 24-hour timeline, the narrative explores the perspectives of the grieving family, the medical team involved in the transplant, and the recipient of the heart. The story is a poignant exploration of life, death, and the profound connections between humans, highlighting the medical, ethical, and emotional facets of organ donation. The author's meticulous attention to detail and lyrical prose bring to life the intricate realities of this life-saving procedure, making it a deeply moving and thought-provoking read.