The World's Greatest First Love: The Case of Ritsu OnoderaThe World's Greatest First Love: The Case of Ritsu Onodera ; World's Greatest First Love: Ritsu Onodera's Affair ; Sekaiichi Hatsukoi: Yukina Kou no Baai ; Sekaiichi Hatsukoi ; Sekai Ichi Hatsukoi - Onodera Ritsu No Baai ; Sekai-ichi Hatsukoi ; Sekai-ichi Hatsukoi - Yukina Kou no Baai ; Sekaiichi Hatsukoi - Takano Masamune no Baai ; Sekaiichi Hatsukoi - Kisa Shouta no Baai ; Sekaiichi Hatsukoi - Le cas de Ritsu Onodera ; Sekaiichi Hatsukoi - Onodera Ritsu no Baai ; Sekaiichi Hatsukoi - Yokozawa

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.