In "Junjo Romantica," high school student Misaki Takahashi accidentally witnesses his older brother being embraced by a stranger, who turns out to be Akihiko Usami—a famous novelist and a close friend of the brother. As their relationship develops, Akihiko becomes Misaki’s private tutor, and Misaki begins to wonder about Akihiko’s true intentions after discovering his latest boys-love novel.
Meanwhile, Hiroki Kamijou, a university professor of classical literature and a friend of Akihiko, is dealing with the aftermath of a failed romance. On the verge of an emotional collapse, he meets Nowaki Kusama, a student asking for academic help to prepare for an upcoming exam. Hiroki initially refuses but later agrees, and a relationship starts to grow, revealing hidden truths about Nowaki.
Separately, wealthy teenager Shinobu Takatsuki learns that his sister has divorced You Miyagi, a colleague of Hiroki. Recalling a past incident where You saved him from a robbery, Shinobu becomes determined to court the teacher, despite You’s attempts to keep his distance. It soon becomes clear that Shinobu is steadfast in pursuing what he believes is their fated love.
"Junjo Romantica" intertwines these three love stories, exploring the challenges and developments for each couple.