Yume no Naka no Rondo

The Minky Momo movie was the one piece of animation released in the English language of the series. It was retitled The Magical Princess Gigi.

From what I've heard, it's mostly pretty close to the original, with minor changes. In it the little princess is sent to Earth and raised by human parents, but for her birthday they give her a magic candy cane which she can use to transform into a young woman as anything she wants. In the movie she'll transform into different stars, a cat burgler, and Cinderella.

Her parents go on a trip to Tahiti but their plane suddenly disappears and Gigi (Momo) goes to find them. She discovers an island with a strange power source everyone is after. Turns out it's the fountain of youth, which is protected by Peter Pan. His father had been a geologist but never put it to use. Peter on the other hand grew up with stories like Peter Pan and the Pied Piper and so now he has built his own paradise after Never Never Land, and any adults who find their way to the island are turned into kids but can live happy, peaceful days after they're led to the castle. What ensues is a battle with the military over the fountain and a struggle for dreams themselves. Meanwhile, I think the princess is falling in love with Peter. It reminded me of Chibi Usa and Helios in many ways. Not just for pink-haired heroines, but too, the theme of dreams (both literal and wishes of the heart).