"Years of study, knowing that despite it all, you may never really be good after all."
Also, she is extremely jealous of Haruka, though quite as flirtatious herself. A few internet sources place her as being Portugese in origin, from a VERY wealthy family in Brazil. As to how accurate that is, one can't say, though we DO know that she owns a Stradivarius. She is extremely intellegent: after all, she made it into Mugen Gakuen, an elite private school...even if it did turn out to be the happy hunting grounds of the heart snatchers.
When I think of Michiru, I think of a quiet mermaid, sitting on her rock by the sea, staring out over the expanse of what could be hers...and yet isn't quite, through miscircumstance.