It's a countdown for the compliation
Pop-up advertisements run the gamut of lame to mesmerizing, and I think this new one from Square Enix is definitely in that latter category here.
To promote the upcoming release of Kingdom Hearts HD 2.8 Final Chapter Prologue (which is out in Japan tomorrow, and the rest of the world later this month), the company put up a stained glass memorial clock at the Tokyo Metro Marunouchi Line in Shinjuku. It's also a perfect way to coax people into visiting Tokyo Disney!
For those of you who can't get out there and check it out themselves, here's a few YouTube videos of the entire setup below. The memorial (and all the other wall mounted advertisements involved) is up until January 15.