Anyone who has watched any anime features knows that they are able to serve a very different function from live action films. What films like Spirited Away, Wolf Children or Colorful are able to do that traditional live-action can't do quite as well, is find a way of integrating folklore and fantasy elements into the lives of its young protagonists in a way that helps them describe their distinct view of the world and the problems they face growing up in it.
In A Letter To Momo, a young girl Momo and her mother have sold up their apartment in Tokyo and gone to live near some relatives on Shio Island. Momo's father has just died in a boating accident, and an unfinished letter that opens only with 'Dear Momo...' doesn't bring about the kind of closure the young girl needs. Three drops of rain from the sky however accompany Momo to the island, where they take the form of ghostly goblins from an old picture-book.
Even though the creatures can only be seen by Momo, the trick with anime films of this kind is that the viewer needs to be drawn into Momo's view of the world, not seeing the line between fantasy and reality, letting the message that lies behind it weave a magic spell without being overstated. That of course if the cinematic art of illusion and A Letter To Momo does this particularly well, creating good interaction between the characters, exploring the opportunities for visual effects, and building it all up to towards an epic conclusion that gets message across sensitively, without preaching or speaking down to a younger audience.