On days when Sunao is ill or simply doesn't feel like attending school, she is summoned to take her place. She came into this world because Sunao wished for a substitute. While no one is aware of her existence, she strives to do her best for Sunao whenever she is called upon. One day, she speaks with Sanada, a classmate of hers. They become friends, but he soon notices that she differs from the original Sunao... he was the first to realize this. She instructs him to speak with her only when her hair is styled half-up. Sanada follows her advice, and they enjoy their time together. As they grow closer, she realizes she has developed special feelings for Sanada. Yet, she is uncertain of what will happen to her... if a replica like her falls in love.