This drama is adapted from the novel of the same name. It tells the story of 21-year-old Toru (played by Nagase Ren) who falls in love with his mother's friend, a married woman named Shishi (played by Itaya Yuka) who is 20 years older than him. They fall in love at first sight and start an underground relationship. Toru's good friend Koji (played by Matsuda Genta) also has an affair with housewife Kimiko (played by MEGUMI), but the relationship is very complicated and difficult to understand. He also has a girlfriend. For three years, Toru listened to Shishi's favorite music, read Shishi's favorite books, and waited for Shishi's call at home every afternoon. He couldn't take the initiative to call her, which was an agreement between the two. Gradually, he became less and less satisfied with such a relationship, and he asked Shishi to live together. Shishi is rational. She knows that everything she has is given by her husband. Shishi knows what leaving her husband means, so she has been vaguely evasive about Toru's request. However, when Toru confessed to her in front of everyone at the party and left, Shishi finally made a decision...