The first time I tried Pocari Sweat I thought it would be some kind of copy of Aquarius by The Coca-Cola Company. Pocari Sweat has a somewhat milder taste than Aquarius and if you fill two glasses with both, Pocari Sweat is more transparent; but in general they are very similar.
But it turns out it was the oppositte, The Coca-Cola Company copied Pocari Sweat. In this screenshot of the movie Back to the Future you can see a Pocari Sweat (down to the right) during year 2015, suggesting that the drink would become very popular in United States in the future:
Zemeckis was partly wrong, Pocari Sweat was never released to markets outside Asia. What happened in 1983 is that The Coca-Cola Company released a similar drink to Pocari in Japan, called Aquarius. During the 80s they were both drinks exclusive to the Japanese market. The next country that was able to enjoy Aquarius was Spain in 1991 to make the most of the Olympics in Barcelona in 1992. Nowadays Aquarius is known in many countries around the world and Pocari Sweat is sold in over 10 Asian countries.
This is one of the most well-known Pocari Sweat commercials (I think it was shown during 2005-2006), in which Ayase Haruka chases a Pocari Sweat train:
Since then, actress Ayase Haruka is one of the models used by this brand.