Hrm.
I think that Origa also did a song for Turn A Gundam, also composed by Yokko Kanno.
They're a splendid team. They create such ethereal music, do they not?
I do not think that Kanno has any vocal talent however. I'm sure that she can play an instrument or two, but she's really a composer more than anything else. A duet with Origa is out of the question too - I think her style is very classical and opera-like. It'd be very weird.