Whenever Sunao’s health deteriorates or she doesn’t feel like going to school, “she” takes her place. Her affair began when Sunao wished for a “substitute.” She has no real existence in the world, but she always tries to give her best for Sunao.
A turning point in her life comes when she meets her classmate Sanada. The two become friends, but Sanada is the first person to realize that this girl is a little different from the real Sunao. She gives Sanada a strange condition: “Only talk to me when my hair is half-up.” The two spend time together, and gradually, the “replica” begins to develop genuine love for Sanada. But she fears what love for a fake replica will lead her to.
