The horrors of change.
Life is long and full of evolution and turmoil, and not everything goes the way we want it to. Sometimes the biggest enemy to our own happiness is our own inability to accept change and failure-- the inability to move on. Accept that who you have become as you will never be who you once were.
Perfect Blue encapsulates this common fallacy of man whilst covering it within a convoluted, distressing, psychological smokescreen which has you questioning your own sanity as much as Mima does.