Taichi Hashimoto first met Mioka Minegishi in the rooftop garden of a university high-rise, where he discovered her walking around the rim of the building outside the safety fence and persuaded her to stop her reckless behavior. Then he came to her rescue in the student cafeteria where she had gotten herself in trouble by starting a nasty fight. These events lead Mioka to become part of the group Taichi hangs out with.
Taichi starts dating another girl from the group, but feels that something is missing between them. By contrast, he feels he can be completely free and open when he’s with Mioka, so he soon begins seeing her instead. She reveals to him that she has been infected with Creutzfeldt-Jakob disease, a form of brain damage that leads to a rapid decrease of mental function and movement, and that she could begin to display symptoms at any time.
Knowing they cannot look forward to sharing very much time, they move in together after discussing the situation with their families. Mioka also says that when she reaches “the end of the end,” she wants Taichi to stop her suffering with his own hands.
They try to make the most of their days while working and going to school, but Mioka, as expected, begins to display symptoms. Once this happens, CJD sufferers can expect quickly advancing dementia and ataxia, and only a few months to live. Day by day, Mioka loses her motor abilities, and her memory continues its steady decline. Taichi is there for her as she struggles with her terrifying condition. When she can no longer get herself to the bathroom, she insists on checking into a hospital?not wanting to be a burden on Taichi. Her illness continues to advance until one day she fails to recognize Taichi. When he shakes her by the shoulders in a desperate attempt to be recognized, she soils herself.
Mioka has become unable to feed herself or to show any expression when, with great effort, she squeezes out the words, “You p-p-promised.” Taichi realizes the time has come and determines to do as she has asked. He dons a black suit, dyes his hair a bright red, and visits her hospital room with a bouquet of roses in order to remove her oxygen and IV tubes . . .