The World's Greatest First Love: The Case of Ritsu Onodera (Japanese: 世界一初恋 〜小野寺律の場合〜, Hepburn: Sekai-Ichi Hatsukoi: Onodera Ritsu no Baai, also alternatively known as Sekai Ichi Hatsukoi: The World's Greatest First Love in the English anime) is a Japanese manga series written and illustrated by Shungiku Nakamura.

Produced by Studio Deen under the direction of Chiaki Kon, the anime series began its broadcast run on April 9, 2011.

The characters follow Onodera's fellow editors: Hatori and his longtime friend (and manga artist he's in charge of) Yoshino, as well as Kisa and the attractive bookstore employee he has his eye on, Yukina.

Written and illustrated by Shungiku Nakamura, Sekai-ichi Hatsukoi began serialization in the November 2006 issue of The Ruby magazine, which went on sale October 13, 2006.

As of August 2014, Sekai-ichi Hatsukoi and Nakamura's other manga Junjo Romantica have switched publications to Emerald magazine.

[9][10] The individual chapters have been released as nineteen tankōbon volumes by Kadokawa Shoten's Asuka Comic CL-DX branch.

The first eight volumes of Sekai-ichi Hatsukoi have been licensed for an English release in February 2015 by SuBlime, a subsidiary of North American manga publisher Viz Media.

The English title is The World's Greatest First Love: The Case of Ritsu Onodera, and volume one was printed in February 2015.

[47] In addition, a special Sekai-ichi Hatsukoi anime short called "Valentine-hen'" was screened alongside the film on March 15, 2014.

The second season opening is "Sekai no Hate ni Kimi ga Itemo" by Shuhei Kita and the ending is "Aikotoba" by Sakura Merry-Men.