Seven Colors of Magic

Nanako was born on July 7th. Her lucky number, of course, is 7. ​This year she’s the 7th student in the 7th class, but she’s been seated next to a wild boy named Kobayashi Kazuki, who has been entertaining crowds secretly as a dancer. As if that wasn’t trouble enough thanks to Nanako’s sister (a dancer herself), they wind up living under the same roof…

Nanairo Magic was the winner of the 1987 Kodansha Manga Award for the shoujo category.

(Source: Manga-Updates)