Very complex plot not intended for kids. At the surface the plot might seems a supernatural teenage story. But for old school Japanese anime lovers they would appreciate and understand the story which discusses childhood trauma and its effect (isolation, anger, emotional numbness and failed relationships).
The plot was extraordinary, using the water and storms as metaphor for emotions and feelings and stressing on the importance of close relationships.
I don't understand the low rating of the movie, I think most of people didn't get it. It reminds me so much of studio ghibli movies, entertaining but with an important message.
A movie that provoks emotions and leave you with a feeling of loss and relief at the same time.