Nodame Cantabile is a manga by Tomoko Ninomiya. It received the 2004 Kodansha Manga Award for shoujo and has been licenced in North America by Del Rey Manga. I recently became addicted to the manga and tv series and so have recently purchased Volumes 1 - 8 of the manga. It's also been adapted into a live action TV drama series and an anime series will begin airing in Japan in Febrary 2007.

Summary from AnimeNewsNetwork: At a top music academy in Japan, Shinichi Chiaki's arrogance is matched only by his top-notch piano playing. But when Chiaki and the teacher get into a fight, he's demoted to the reject class. Chiaki is left to pursue his dream of being a composer while surrounded by a bunch of loser musicians and one annoying girl, Noda, who has proclaimed herself Chiaki's girlfriend. It doesn't help that Noda, who insists on being called Nodame, lives right next door to him.