This is one mighty curious aspect of the Japanese retail landscape; the incessant - obsessive, even - drive for new canned and bottled drinks. No flavour is too obscure, no concoction too strange not to be mixed, canned and put on sale in vending machines and convenience stores. Most of these appear, sell for a few weeks or months, then disappear again without a trace.
Many of these novel drinks actually taste quite good. Of course, tasting good is probably not nearly enough for them to survive in the long run. We consumers are a conservative bunch, and we won't switch drink type (or political party, or keyboards) if it's just a little better than whatever we normally drink. It'd have to be substantially better (or a lot better marketed) to really have a chance. Still, new and strange drinks are always fun to try.