Lovers' Concerto: Senritsu no Majutsushi (2007)

Blurb:
Music has always been a powerful source of stimulation. Kyoichiro is a hot new pianist known as "The Conjurer of Melody" who possesses an extremely arrogant "bow before my greatness" attitude. So it’s no wonder that Kazune, Kyoichiro’s manager and lover, can’t help but feel she is nothing more than his erotic plaything. Will she be able to prove to Kyoichiro that she is more than just an instrument of pleasure? Or will she continue to be swayed by his intense melodies of desire? An erotic romance that will stimulate your senses with the rhythm of passion!

Source: www.anisearch.com/manga/2941