Episode 0: Ritsu and Takano used to date back in high school, but broke up due to a misunderstanding. This is that story.
Alt. title: 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
Aired: Mar 22, 2011 to Sep 27, 2011
Original creator: Shungiku Nakamura