Ok... I need some help identifying a song..

[AyuMayu]

Ok... It's kind of obscure, and it doesn't help that I don't know the title or the artist... But, it's a guy "band" (not really sure if it counts as a band or not, since I saw one guy singing). But it played during a commercial of some drink like Pocari Sweat or something LAST SUMMER (04) in Japan. It was a pretty well known commercial, the drink was popular and the commercial played often.. It was summer themed, and the reason I remembered was because of fairyland. The commercial was filmed on a beach, and there was some guy singing (maybe multiple guys). I really liked the song but forgot about it for a while, and didn't really have a proper place to ask until now.. So.. Here I am.. I know it's very obscure and I provided like NO information but if anyone has the slightest clue what I'm talking about... I would REALLY appreciate it..