Wow, this one went by so fast, before I knew it it was over.
Frill's plan was to get Ruby cast as Ai.
To achieve that, she set up individual auditions as a way to bring out Ruby's potential and get Akane removed from the role.
Frill really is an interesting woman.
Since they're all popular actors who really get into their roles, they instantly understood the meaning of this movie, and I caught a glimpse of the terrifying nature of actors.

Season 3, Episode 34: Aqua... Ruby... It can't be stopped now. | mentamago's post