I myself am an Ayu and Hikki fan, even though I haven't heard loads of Hikki's songs. I agree that it's hard to compare them as their styles are completely different. Also, I hold both of them with extremely high respect as musicians and for what they've done. Personally I do prefer Ayu to Hikki as I much prefer a higher voice aswell, although all my friends in school think she sounds like a chipmunk
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