Okay well "Perfect Blue" is a very distinct anime and it is very much open to any type of interpretation you may wish to perceive. I loved this "Perfect Blue mainly because it touched me on a personal level as identity and mental illness are key aspects of the movie and I have always found these aspects intriguing.
Never again, no never again will I witness an anime movie (ova) as good as "Perfect Blue". Throughout the whole anime movie I was emotively impacted as my heart was racing, I constantly got goosebumps and became trembly during some drastic scenes. I absolutely loved how it stepped outside of the box by unconventionally challenging the audiences perceptions on identity and mental illness through numerous horrific and psychological aspects. I especially loved the aspect of 'inception' and generally I don't like overly confusing animes such as "Ergo Proxy" (still an awesome anime), though this one is definitely an exception. "Perfect Blue" undoubtably has to be one of the best animes I have ever seen, I'd say it easily sits up there with "Elfen Lied", "Clannad", "Monster" and "Death Note" (my personal fav's). I don't think I have ever been more enthralled for 1h 50mins whilst watching anime XD. The only downfall to the anime if you can really count this as one, is that the animation (graphics) isn't top notch. Then again, its made in 1997 ~ So I commend the creators on the traditional methods used to create the movie ;)
Rating; 10/10
Now explaining it for more insight: (Spolier Below)
Basically from my interpretation Mima whom once was a famous Pop Idol decides to try to become a actress so she can become furthermore rich and famous. During her metamorphosis she's starts to doubt her sense of identity and as a result suffers from extreme forms of mental illnesses (esp. schizophrenia), hence the symbolic form of her old "pop star" self, that she keeps seeing- metaphorical meaning.
Rumi her manager plays as the "bad person" and she is the allegory to the movie. Rumi missed out on her opportunity to become famous, thus she perceives herself as Mima and commits all the murders in order to gain revenge on all the people who tarnished Mima' reputation... or what she believed was her own reputation. Rumi suffers from mental illness (dissociative identity disorder) and never overcomes this as she's stuck in her own reality- this is imperative as its through Rumi's hardship that Mima finally succeeds in the end is able to find her true identity.
Uchida (fish looking guy) is the metaphor to the story, he is very much like Rumi, but due to his mental instability becomes overly obsessed and insane with Mima. Hence its seen that Uchida is a very lonely, depressed and insecure individual who has never had someone to love and care for him. Therefore is obsession of roots from a source of autism, thats why he looks weird and is addicted to Mima. Regardless, he is a very significant symbol for Mima as he highlights the importance of never forgetting about your past and who you truly are deep down as a person.
In the end, it becomes evident that through Mima's experiences as both a Pop Idol and Actress, she finally understands who she truly is. Its also through Mima's experiences and encounters with both Rumi and Uchida that she endures psychological hardship, but learns a valid lesson in finding her self. Hence the main message of the movie is that "life is a continuous learning experience" as Mima starts to learn about her own identity as a person. The movie also is symbol in expressing how mental illness is a drastic issue that controls an individual to perceive the world in an unrealistically sense. Another key point is that through transitions (Mima's journey) one can find who they truly are. This is inevitably impacted by experiences and attitudes that an individual will encounter through their life long journey.