This film is definitely on my watch list. I saw the trailer and thought it was okay, but I figured I'd watch it. Then I learned the song heard in the trailer is a cover of her own song from ~10 years ago, and her fans encouraged her to make it into a book. She did, and the book became the movie. So her fans have a long journey to be proud of.
Keeping in mind that the music video (and song) led to the book... the music video may have story spoilers for the movie, since it's the original concept the rest comes from. Who knows, though. So here's that video.
https://www.youtube.com/watch?v=I0MT8SwNa_U
Also, if you're a fellow dbzer0 user (the instance I'm on and the community you're reading this on is hosted on), this instance's music comm (disclaimer of bias: I started that comm) featured this song as its Song of the Day (read: I posted it) four days ago.