Mika, a high school student, had no interest in boys or sex. One day, she was fascinated by a woman in a photo she found at her best friend Mayu's house. It was Mayu's mother, Natsumi. Later, when she visited Mayu, she found her mother out and Natsumi welcomed her. Then, Mika confessed that she was different from normal girls, and Natsumi gently kissed her...