The famous Sonikku Akua. (Sonic Aqua, for the regular pronunciation of it) This is a type of cola produced by Asahi.
Unfortunatly, it is grape-fruit flavored. Yes, the famously bitter, annoying, super-citrus-overload fruit that NO ONE wants...they make a cola that tastes just like it.
Someone in the USA tried it, and published a review at some point, which (predictably) stated that it's rather awful. Was it some sort of limited promo? If it was sold and expected to last at retail...it isn't much a wonder that there are not many cans of it about.
Still, it remains the most 'famous' Sonic food from Japan.
Let's Try it!
Whoops! Its Sour.
Photo by SegaFreak
Photo by SegaFreak
Front and backside of the drink, it's the left one in the pictures.