The story takes place in the first 20 years of the Showa era, during the last few months of the war that engulfed the world. In a secret Imperial Army research facility, experiments were being conducted to revive soldiers who had been injured and left unable to live as normal human beings. However, these experiments were also aimed at using these soldiers until they completely expired. The only success of these experiments was a young girl named Rei, who had a terminal illness and was being housed at a sanatorium in Izu. A young genius scientist named Ozaki used her congenital immune deficiency to achieve cross-species organ transplants between humans and pigs, resulting in Rei losing everything that made her a girl in exchange for her life. This is a record of the last few months of the unfortunate girl's life and the events that took place around her.