I understand this is a parody, but what is she doing behind her back, since there is no bra to take off?

Maybe trying to get her Rosa Mystica.

This might explain it:
post #53420

Zekeltarfos said:
This might explain it:
post #53420

No, I got the reference, it's just weird to have a topless girl reach behind her back for no discernable reason. I haven't watched Rozen Maiden through the whole way, but I don't think Rosa Mysticas are pulled from their backs.

They aren't, she just needs to be in that pose for the sake of the parody.