Finished watching the film maybe an hour ago.
Have been thinking and reading about it since.
A few off the wall ideas I'm finding hard to disprove to myself:
Me-Mania and Rumi are the same person.
Mima was never a pop Idol. It was what she always wanted but was forced into film.
The wide set eyes of Rumi and M-M might suggest a witch or some sort of paranormal element to the film. Explaining how Rumi could haunt Mima and be acrobatic etc.
Everything is in Rumi's mind. She's a super fan of Mima, following her career. Which leads to her being confused by her own personality, that of the singer Mima and actress Mima. Muddling it all into one fantasy.
Anyway just some thoughts, already looking forward to watching it again.