Sekaiichi Hatsukoi: Onodera Ritsu no Baai has been published in English as The World's Greatest First Love: The Case of Ritsu Onodera by SuBLime since April 14, 2015.
The Emerald manga magazine, launched by Kadokawa, is the real-life version of the one featured in Sekaiichi Hatsukoi, the only difference being that the fictional Emerald features only shoujo manga while the real-life one features both shoujo and yaoi titles.