As absurd as this sounds, there could be a possibility of Kasumi's
metallization. No doubt many would disagree, but just remember:
Metal-heads are everywhere, you neigbour could be a metal-head, your
brother, your sister, heck even your MOTHER could be one. Not all
metal-heads have long hair, wear black death metal shirts, and start
mosh pits out in the middle of the street.

Being a seasoned metal-head myself(or bevon as we call 'em over here), I
know that metal-heads come in all shapes and sizes. As the metal-head's
anthem, Metali Militia by Metallica, states:

"We are as one as we all are the same
 Fighting for one cause
 Metal and Leather are our uniforms
 Protecting what we are
 Joining together to take on the world
 With our Heavy Metal
 Spreading the message to everyone here
 Come let yourself go"

So, Kasumi's musical preference could be metal. Even my mother, aged 49,
and who listens to classical, likes "Master of Puppets". I can just see
Kasumi headbanging while everyone is out of the house......