Two OVA episodes featuring additional stories.
Episode 0: Ritsu and Takano used to date back in high school, but broke up due to a misunderstanding. This is that story.
Episode 12.5: Hatori and Chiaki go to visit the latter's family. It's really awkward in many, many ways.
Onodera Ritsu has just transferred from his father's publishing company to Marukawa Shoten. Assigned to the shoujo manga division, he crosses path with the person he'd least expected to meet. Takano Masamune is the editor-in-chief of the division Ritsu's been assigned to, and the two seem get off on the wrong foot right from the very start when Takano unexpectedly kisses him. However, there is more to than what meets the eye: Takano is actually Saga, Ritsu's senpai and high school love, whom Ritsu had thought to have played him for a fool by taking his affections for granted when he confessed and summarily dumped him.
[Source: MyAnimeList]
After the rejection of his first love Yokozawa Takafumi goes out drinking all by himself. The next morning he wakes up naked in a room with Kirishima Zen, the editor in chief of Japun, unaware of what transpired the previous night. As if handling the rejection from Takano Masamune wasn't bad enough, now he has to deal with the capricious Kirishima who uses his embarrassing pictures to blackmail him into going out with him.
[Source: Anime News Network]
Animated short with an original story that was screened alongside "Sekaiichi Hatsukoi Movie: Yokozawa Takafumi no Baai."
