Pavane for a Dead Girl Vol 1

From the Tokyopop edition

Takenomaru Sagami is a violinist prodigy who's on a quest. While attending a music school his father teaches at, Sagami enters into an ominous contract. He must pursue 12 girls from whom he must obtain the 12 tears of Maria. By giving them each a brooch which changes colors when the girl's feelings for Sagami change, he will attempt to make them fall in love with him. Unfortunately, soon after, each girl will suffer a terrible fate.

Source: Anime News Network Encyclopedia