Originally Posted by
ksandness
I've never seen V8 juice in Japan (that doesn't mean that it doesn't exist, only that it's not conspicuous), but the Japanese go-to hot weather beverages are the canned soft drink called Pocari Sweat (like a slightly salty lemonade, available in convenience stores and vending machines all over) and mugicha (iced barley tea).
I might have seen V8 at a Meidi-ya, or one of the more low-key depachika supermarkets, but a very good substitute (and not as salty either) would be one of
Ito En's products (in Japanese)
Ito En2 (in English).
１日分の野菜 "Ichinichibun no yasai" refers to a day's worth of vegetables, so that would be the closest equivalent to V8.