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… Source: Manga-Updates