As Misaki Takahashi and Akihiko Usami's relationship matures over three years, new challenges emerge, including a looming rival that sparks Usagi's concerns about Misaki's affections. Meanwhile, Ryuuichirou Isaka's interference in their love life contrasts with his own struggles in romance alongside his reserved secretary, Kaoru Asahina. Nowaki Kusama and Hiroki Kamijou find their busy careers straining their time together, inviting doubts and anxieties. The significant age gap between Shinobu Takatsuki and You Miyagi tests their bond, but mutual understanding helps dissolve their insecurities. Amid these intricate relationships, Junjou Romantica, Junjou Egoist, and Junjou Terrorist couples return alongside the newcomers in Junjou Mistake.