I assume it's the D Boss, but a "successful" attempt.
That's a really, really cruel fight to screw the camera up on you like that. And it only gets worse... purposefully worse. Apparently things are "still going on" whent he screen fades to black (so if you fail to keep up even then you'll die)... so, uh, get good at rhythm games. If I wasn't so in love with the overall spectacle, I can tell I'd hate the hell out of fighting it. Here's hoping there's an "easy mode" as generous as it was in NieR.
I love the song. ;_;http://youtu.be/rCIU0nnoa7I
Cute moment with the dragon singing a tune about himself.