At the beginning of the 21st century, the drop in the birth rate creates serious problems. Seiji, our hero, is born into this world. By the time he is an adult, there are more robots than human beings. He was a professional pianist, but three years ago he suffered an accident. Since then, he hasn't been able to play the piano professionally. He lives with Yuna, an android, who is the same model as the nurse who took care of him in the hospital. Seiji treats Yuna like a human being-rather than a robot. One day, he decides to teach Yuna how to play the piano. His effort works, and Yuna learns to perform at a higher level, especially after Seiji takes her to a live concert.