Rio Kijima, a once-promising literary talent now drowning in debt, encounters a former classmate named Shiro Kido at a college teacher's funeral. In their university days, Kido envied Kijima's award-winning writing ability, an envy that ultimately convinced Kido he lacked the same genius, leading him to abandon literary aspirations for a career editing erotic novels. At the time of their reunion, Kido has just been thrown out by his girlfriend, leaving both men adrift and at low points in their lives.

Recognizing that they each possess something the other needs, Kido offers Kijima a place to live, and in return, gives the struggling writer a new and controversial purpose: to write pornographic novels. To train Kijima for this drastic career change, Kido introduces him to an eccentric and renowned author of erotic fiction. This master challenges Kijima to prove his seriousness by performing a sexual act on Kido, an event that blurs the lines of their professional arrangement and ignites a tense, passionate relationship between the two men.

As they collaborate, their dynamic shifts from a professional transaction into a toxic and all-consuming craving, driven by mutual suffering and a volatile mixture of jealousy, lust, and dependency. While Kijima, who is haunted by his own perceived failures, begins to open up, Kido finds himself torn between his genuine feelings for Kijima and the pressure to conform to societal expectations. Ultimately, Kido chooses a conventional life, marrying a woman and having a child, leaving their intense affair unresolved. The narrative, framed as Kido's recollection while he is separated from another writer in the present, explores the lingering "what if" and the deep, indelible mark their relationship left on both of their lives, concluding on a bittersweet note where Kido still harbors regrets for not following his heart.