I could honestly just add details to this forever, but I have to draw a line in the sand sometime lol.

Nü Jersey requires that its inhabitants participate in mass rituals of song and dance, as per the traditions of their theme park mascot ancestors.  Kaye, an outworlder wishing to avoid these rituals, exploits a loophole by joining a metal band in need of a backup growler.

This is also her magical girl costume.  The two uses may or may not be related to each other.