"Candy Candy is primarily a love story. Candy's first love was a character named Anthony Brown, but the series is remembered by the majority of fans as a result of her heartbreaking separation from her true love and soulmate, Terrence "Terry" Grantchester.A recurrent story arc in the series is the "Prince of the Hill", a mysterious boy Candy encountered once as a child. His identity is revealed in the last pages of the manga and in the last chapters of the anime."--Wikipedia
"Candy Candy" is written by Kyoko Mizuki and drawn by Yumiko Igashari. The manga ran from 1975 to 1979 while 115 episodes were aired from 1976 to 1979. This might be the grandmother of reverse harems unless there is an older anime or manga that I'm not aware of. I havn't actually seen this but it aired in our country years ago. Some of the episodes are in CR but lo and behold when I finally decided to watch it, it was already removed due to licensing. sob! Speaking of licensing, the writer and the artist had legal disputes with the copyrights. The long battle ended with equal rights between the two which is a first of it's kind in Japan, but the "Candy Candy" was never given a proper ending that fans had clamored for. I kept on thinking that the girl looks like "Lady Georgie" and it turns out they were from the same artist.
Related: Candy Candy - Haru no Yobigoe (movie)(sequel); Candy Candy - Candy no Natsu Yasumi (movie) (sequel); Candy Candy Movie (remake)