Kisa sees Yukina, the Marimo Books employee he has been attracted to for a long time, selling the latest book he has edited. Tall, handsome and charming; Yukina is extremely popular among girls, who are easily convinced to buy the books he is selling. Kisa does not believe they could ever be together. Checking the sales of his book, Kisa notices that the sales are very high at Marimo Books, as they have been for his previous books too. They are finally introduced to each other by Yokozawa in the bookstore. Just as Kisa is leaving the store, he runs into a persistent ex-lover. After being rejected yet again, the man is about to hit Kisa when he is stopped by Yukina, giving Kisa an opportunity to flee. Later on, Yukina happens to find Kisa in the little-known cafe he had run away to. They talk, and Yukina correctly guesses the authors Kisa has been in charge of, saying they had a similar atmosphere despite being very different books. He is also astounded by Kisa's youthful looks after learning he is actually 30 years old. Yukina reveals he himself is a 21-year-old art student. As he plans a fair to promote Kisa's latest book, it begins to rain. Kisa, however, is lost in thought and doesn't hear Yukina asking him if he has an umbrella. Noticing this, Yukina leans in and kisses Kisa.
Sekaiichi Hatsukoi follows three couples that are interconnected within the manga industry, with each being subject to the budding of first love.
