Oh my god oh my god ohmygodohmygod it's so sweet. It's so beautifully written. Your insight into their characters is amazingly clear, even in this short little piece. Won't you please write another chapter, where they're all grown-up and Killua is playing the piano, and they both remember this? A glorious little continuation? :P
Regardless, it's achingly lovely!

...
actually this could be interpreted as an insult :
it sounds empty
it sounds like you
...
you are ( sound ) empty ...
I still like it .
I will just in terpret the story like that and see it as gon saying that he likes killua no matter what in a cute kinda twisted way and ignor the part of killua blushing at the end .
you have my fav

Kawaii! i luv it