what chocolate does mello eat? it’s been bothering me for quite a while now
I don't think the brand is actually a real brand (or at least not one I've identified), but it should be dark chocolate because that's what makes the crunchy sound when you bite into it.
I think @onceuponadisembo has solved the mystery!
Meiji Black Chocolate bars have the dark exterior as well as the foil wrapping, and they do feature the correct subdivision of the bar into 3 segments per row! And most importantly:
Mello's chocolate bars have a black wrapper but the ends are wrapped only in the tinfoil, rather than the black wrapped going all around. This does appear to be the case for Meiji bars as well, even if less obviously so: