A Good Beginning Makes a Good Ending.
In the Emerald Editing Department of Marukawa Bookstore, Ritsu Onodera works as a shoujo manga editor under his boss and also his "first love," the editor-in-chief Masamune Takano. While struggling to work as the production assistant for a new magazine while resisting Takano's authority, Onodera unexpectedly encounters Takano's friend, the sales department employee Takafumi Yokozawa...!?
Aired 08/10/2011EP 1 - A Good Beginning Makes a Good Ending.

Sekai Ichi Hatsukoi - The World's Greatest First Love Season 2
First loves are messy. While settling in as a shoujo manga editor at the famous Marukawa Publishing House, Ritsu Onodera is quite troubled. Working under the stern and superb Masamune Takano is hard enough as it is. However, Masamune is not only Ritsu's first love from middle school but he also suddenly declares that he will make Ritsu fall for him again.
Unknown to them, another editor in the department, Yoshiyuki Katori, is in a relationship with the popular manga artist Chiaki Yoshino. The carefree Chiaki fails to notice, however, that his high school friend—Yuu Yanase—thinks of him as more than a friend. The stoic but caring Hatori will not surrender his love so easily.
Falling in love for the first time when you are 30 is certainly troublesome. Shouta Kisa, yet another editor, is going out with 21-year-old Kou Yukina, an art student. Despite Yukina's assurances, Kisa cannot help but doubt whether someone like himself is truly worthy of his younger, "sparkling" boyfriend.
(Source: MAL Rewrite)