Really enjoyed this movie who is about the feeling of understanding why "my mum went to save a perfect stranger little girl from the flood but died leaving me behind" and the understanding to help other.
There are some other day to day situation into this movies too , who could have been a main subject by themselves, such as the consequences of social media can have on a person, for good or bad and how quickly it can change either way.
The promise of protection towards a friend, Suzu/Belle have mainly ( but not only) 2 persons who look after her and always by a side to encourage/guide her.
And, the other subject, child abuse/domestic violence by parents.... but this suject in the movie, is more about standing up for yourself (or for others who struggles).
There is also , a modern breeze of the fairy tale beauty and the beast. Soundtracks and song are sublime, technically beautiful and colourful, nothing less.
I wisely recommend to go and watch this anime, and let yourself travel through a river of various feelings, colours and musics. An adventure by itself. Bravo!