Elbe no Kanmuri(1978)

Elbe no Kanmuri

For Kitty, a young girl raised in an orphanage, the spring of her fifteenth year marks a major crossroads of destiny. She can't help but wonder what kind of life she will have with the apprenticeship she is forced to take...... if she's lucky. Then a something big happens to her, and in the blink of an eye, she becomes Cinderella, and the curtain opens on a brilliant grand romance.

(Source: Hana to Yume, translated)

Note: The only tankoubon volume contains the first six chapters.