This is the one you had to buy a manga volume to get, and Nakamura Shungiku knew exactly what she was doing. Two episodes, three segments, and every fan already knows which one they're waiting for. Romantica gives you Misaki still refusing to say the thing out loud while Usami says it constantly and shamelessly. Egoist runs on Hiroki's temper doing the work his honesty won't, with Nowaki absorbing all of it like it's affection, which it is. Terrorist stays the quiet knife of the three, Miyagi's age gap guilt against Shinobu's absolute refusal to be talked out of anything. No plot to catch up on, no arc to resolve, just concentrated time with couples you have opinions about. Bonus material that treats the fandom like it earned this, because it did.
Three separate stories make up this two-episode OVA, a romantic comedy-drama released with the limited premium editions of volumes 16 and 20 of the manga. The first, Junjou Egoist, puts Kamijou Hiroki and Kusama Nowaki aboard the Shindai train for a trip together. The second, Junjou Terrorist, turns to Miyagi You and Takatsuki Shinobu, who struggle to come to terms with the difference in their ages. The last, Junjou Romantica, finds Usami Akihiko and Takahashi Misaki looking back on their early days, when Usami helped Takahashi prepare for his college entrance exams.