I find the animation impressive and conveys the dream-like world of children.  The mix of  animation with a real person (girl) makes for great visuals and with accompanying music that goes well with the theme. I think that everyone, at some point in their lives, go to this phase, collecting and keeping things but in the case of the girl, she is portrayed as collecting  firefly-like formations that appear to form into animals and other shapes.  It doesn't take long for her to realize though that she had to set them free which I think is a  candid gesture on the side of the child.  Dreamlike and charming, do check out this film.