College student Haruhiko Kuzumi is broke and without insurance when his bicycle accidentally collides with Renjiro Kijima, a novelist who fractures his arm in the fall. Unable to pay the medical bills, Kuzumi accepts an unusual arrangement from the injured author: he will become Kijima's amanuensis, taking dictation of a new manuscript by hand because the older man refuses to use modern technology. Only after agreeing does Kuzumi discover that his new employer, who writes under the pen name Renjiro Kijima, is a specialist in erotic fiction. As Kuzumi transcribes increasingly explicit passages, he finds himself aroused by Kijima's low, alluring voice. Kijima teasingly notices the younger man's discomfort and offers to resolve it with his mouth, a joke that nonetheless shatters the barrier between them. What begins as a transactional debt shifts into something far more complicated as Kuzumi develops feelings for his enigmatic, often aloof employer. However, he soon uncovers a betrayal: Kijima has not been dictating a new work at all, but rather reciting previously published material. Devastated but determined, Kuzumi confesses his love, forcing a confrontation with the truth. Kijima, struggling with a deep creative block and unable to write, has been living a lie. He decides to abandon his career and return to his rural hometown, but Kuzumi refuses to let him go without one final request: that Kijima write a story just for him.

The narrative expands beyond this central volume through related works. The prequel Mood Indigo explores Kijima's past as a struggling pure literature writer facing financial ruin. At a university professor's funeral, he reunites with former classmate Kido, now an editor of pornographic novels. Kido offers Kijima a lifeline: abandon literary ambition and write erotica for a living. Desperate, Kijima accepts and is apprenticed to a veteran smut author named Kijima. This arc details his reluctant descent into the genre, his fraught creative partnership with Kido, and the complicated feelings of jealousy and desire that develop between them as Kijima must confront his own sexuality to produce his work. The final installment, Playback, follows the aftermath of the original story as Kijima and Kuzumi attempt a long-distance relationship after Kijima returns to his hometown. When Kijima suffers another hand injury, he hires a local young man as a new amanuensis, recreating the circumstances of his first meeting with Kuzumi. The arrival of a jealous Kuzumi forces the couple to determine whether their love can survive the distance and their own insecurities. The primary characters include the cynical and self-destructive Kijima, the earnest and persistent Kuzumi, and Kido, Kijima's married editor who shares a complicated history with the author.