Anmitsu Hime

One of the earliest shoujo manga of all time, Anmitsu-hime began its serialization in Shoujo Magazine in 1949. Set in a dreamy, idealistic Edo-period Japan intended to comfort children during the U.S. occupation, the story follows a young princess in a long-sleeved kimono. The princess, Anmitsu-hime, and other characters are named after sweets and desserts.

The series was incredibly popular, running in multiple magazines until 1962. It inspired an anime series, two movies, three TV dramas, a radio drama, and a video game, as well as a manga reboot in 1986.

(Source: MangaUpdates)