Chinatsu's Voice

The series takes place at a certain Japanese location, where a girl moves in with her aunt to a new house after experiencing some more or less shocking events back home. There she meets a boy named Fuyuki, who she from then on spends a lot of time with. The thing special about Chinatsu is her voice, a voice which many seem to have heard before, but from where? What's so special about this girl, and what'll happen in the future?