Itazura Choucho Mischievous Butterfly

Synopsis

Sakura, a 1st-year student at a music high school, loves playing piano. She also quietly loves her friend, Nanoha. Nanoha has adored listening to Sakura play the piano ever since they were children. As the yearly music competition for upperclassmen comes around, Sakura will have to deal with her passion for both the piano and Nanoha. (Source: MangaHelpers)