In fact, reader Amelia set her computer's clock ahead one day at a time, causing the site to play a more complete snippet of music each day, and the Shibuya background to become clearer.
It's pretty clear that whatever this countdown is, it has something to do with The World Ends With You. Of course, we don't want to jump to the conclusion that it's a sequel yet – it could be a port to a new platform, some kind of mobile spinoff, or even an anime or manga. Let's keep our expectations in check by remembering the last time we saw these characters, it was in a Kingdom Hearts game.
[Thanks to everyone who sent this in!]