Sekaiichi Hatsukoi OVA
Japanese title: 世界一初恋 OVA
Alternative titles: Sekaiichi Hatsukoi Episode 0, Sekai-ichi Hatsukoi: Onodera Ritsu no Baai, Sekaiichi Hatsukoi Episode 12.5, Sekaiichi Hatsukoi: Yoshino Chiaki no Baai, Sekai'ichi Hatsukoi
Type: OVA
Source: Manga
Episodes: 2
Status: Finished Airing
Aired: Mar 22, 2011 to Sep 27, 2011
Duration: 21 min per ep
Rating: PG-13 - Teens 13 or older
Studios: Studio Deen
Producers: Kadokawa Shoten
Licensors: Funimation
Genres: Boys Love

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.