Kimiko is using Yuki's traditional distress noise rather than her own traditional "Reeehhh".

Piro speaks:
uwah... oh crap. hahaah, you're right. How the hell did i mix that up??
tho 'rheee...' might not sound quite right either.
Honestly, the weird sound thing in games (which then move over to anime, its in the new AIR series too. Kamio has all sorts of weird ass little sounds she makes :) is kind of a strange thing to begin with, and i should be consistant.
might change, might not. Hapenstance being what it is...