Okay, to be fair, Mizhara's bunny outfit is by far the most original I've seen in a non-cosplay-centric manga in forever. Also, her keeping their promise, while not progress, does show she has changed a little. With enough blood, the ocean would turn red, I guess.
Now, all the positives said, firstly, why did Mizuhara lie? She gains nothing by not saying "No, I never tried a bunny cosplay before." Would Yaemori think less of her? No, she'd just say "Well, you ARE an actress, I doubt there are too many plays that require bunny cosplays. I bet you're a little excited though, since it's your first time!"
Second, why is Kazucuck still Kazucuck?