Misaki Takahashi and Akihiko "Usagi" Usami's three-year relationship is progressing smoothly, but every great relationship has its problems, and theirs is just beginning. As Usagi worries about a new rival, he fears Misaki's commitment to him. Meanwhile, Ryuuichirou Isaka has always meddled in their love life, but his own relationship with secretary Kaoru Asahina is struggling. Asahina keeps their personal and professional lives apart, causing issues between them. Nowaki Kusama and Hiroki Kamijou's busy careers are causing them to drift apart, and doubts start to grow between them. Shinobu Takatsuki and You Miyagi's 17-year age gap continues to create barriers in their relationship, but they are slowly breaking down their walls as they get to know each other better. Fans of Junjou Romantica, Junjou Egoist, and Junjou Terrorist will be delighted with the addition of Junjou Mistake.