Kajiura Yuki (of course) on the piano. 11 different singers, without counting Kajiura, who also sings a couple of lines herself. One opera singer among them. They sing different lines each, it's not a choir. Nice choreography - not complicated since they're also dancing, but nice. What I didn't really like is the costume colors, but the overall result is still perfect.
At first, I thought it was a simple counter advertisement that looked like a countdown. But I was actually the 54321-th person to visit that webpage! Reloading it in a new tab showed a different number :D
What did you say? I should try the lottery today?... Nah, this kind of thing never works when you actually have something to earn from it. ☹