Doron(1972)

Doron

The trouble started when Daisuke, a third-year middle-school boy, mistakenly gave the love letter he had written for Rie to Yukino instead. When Yukino's best friend, Kyo (Miyako), blames Daisuke for hurting Yukino's feelings, he tells Kyo that the real recipient of the letter is her! Also includes two other stories.

(Source: Shueisha, translated)