Jun Ichikawa film - How To Become Myself

I've just seen a great Jun Ichikawa film, 'How To Become Myself'. It's a really sad and moving film about what it's like being a teenage girl. It looked as if it might be based on a novel or short story - I wondered if anyone here might know whether it was, and if so who the author is? I'd love to read some more of their work, if possible.

It's based on a book by Kaori Mado.

Thank you! With that information I managed to find this: http://anutshellreview.blogspot.com/2007/09/japanese-film-festival-masterclass.h....

"Ichikawa Jun: First of all, the author of the story (Kaori Mado) is a lady about 30 years old now. She's now a staff of an advertising agency for mobile service provider NTT Docomo, one of Japan's largest. The author is brought up in a girl's only school from junior to senior high, and the book is something like her autobiography. I read the book and I loved it, especially the themes of the "fake" and "real" me. Each time I think about the "fake" me, I think about the author."

Unfortunately it looks like it hasn't been translated into English...