Princess Knight, also called Ribon no Kishi (the original title) was the first shoujo manga. It was written by Tezuka Osamu (in Japanese name order here), who is sometimes called the "God of Manga" due to his famous works Astro Boy, Adolf and Phoenix- all three of which have been released in the US. First, it was serialized in "Shoujo Club" starting in 1953. Sequels to it ran in Nakayoshi (a manga magazine popular with girls in Japan) in 1958 and 1963.
The story is a pretty simple one. In heaven, all the souls waiting to be born are lined up, waiting to be assigned a sex, which is accomplished by means of eating a heart. A mischievous cherub known as Tink walks to an unsuspecting soul and feeds it a boy heart, reasoning that it looks male. However, god has other plans, feeding it a girl heart saying it's definitely a girl. After the heart is eaten, the baby informs him that he already ate a heart. Tink is found out as a culprit and sent to earth.
Meanwhile, in Silverland, a baby is born to the queen. It is a little princess, but the doctor has such a lisp that they can't tell if he announced a prince or a princess. Everyone wants a prince to rule, so that the evil Duke Duralumin and his lazy son, Plastic, don't get the throne. By the time the King finds out, it's too late, everyone thinks a prince has been born. Poor Princess Sapphire has to be a boy in public and only do girlish things in secret but Sir Nylon, the evil servant of Duke Duralumin ,is always trying to catch her out! There is a lot of other trouble involving secrets, magic and the Prince of Goldland, Franz Charming, in the six volumes of the story, but it is not good to tell the entire story in the synopsis.
A note before we go to background and anime, all manga story information was gleaned from two volumes of the Kodansha Bilingual Manga, a special edition to help Japanese students learn English, by having English in the bubbles and Japanese out to the side. Kodansha is the company that publishes Nakayoshi, so it is one of those versions. Now to background. When he was young, Tezuka enjoyed the Takarazuka Revue, a musical theater in which all the actors were female and played all parts, even the male ones. He is said to be inspired by this revue. It is also common to say that he was influenced by Disney, the great American animator. The large eyes, the Snow White like talking to doe eyed animals and overall cuteness points to such an influence. Also note the mineral naming theme-Princess Sapphire, Silverland, Goldland, Nylon, Plastic, and even Duralumin is thought to have stemmed from Aluminum. Note that all the bad characters such as Nylon, Plastic and Duralumin don't have valuable names.
There was an anime version of the story that aired in 1967. It was made by Mushi Productions, a production company headed by Tezuka. The name is because the young Osamu loved insects. In Japanese, insect is 'mushi'. Sometimes Osamu would write the last of his name with the character for 'mushi' which is a strange and interesting pun. It ran for 52 episodes. It was shown in Japan, Australia, Spain, Canada, Mexico, and parts of the US. However, this seems to have happened in the 70s. There was also a 'film' made by editing some of the episodes together called 'Choppy and the Princess," Choppy being a very strange name for Tink.
It is always interesting to trace an artform to its roots. I was surprised to know that until the Nijuuyo-nen Gumi, ( 24 Year Group, often nicknamed in English as the 49ers, because the 24th year of the Showa era is 1949.) most shoujo manga artists were male. 1949 was the year many members of the group were born. They started doing fabulous things to shoujo manga in the 1970s with such work as The Rose of Versailles by Ikeda Riyoko, also author of Oniisama E, often called Brother, Dear Brother, The Heart of Thomas by Hagio Moto and Song of the Wind and Trees by Takemiya Keiko. Tezuka set the stage for them, and they set the stage for our new generation of shoujo authors such as Watase Yu, author of the popular Fushigi Yuugi and Takeuchi Naoko, author of Sailor Moon. The infomation for this article was gathered from Dreamland Japan for the interesting bits about Tezuka and from http://www.matt-thorn.com/sexual_ambiguity.html for infomatuon about the 49ers. This page gave manga info: http://en.tezuka.co.jp/manga/sakuhin/m029/m029_01.html and this page anime infomation http://www.alphalink.com.au/~roglen/princess.htm