It's a visually wonderful story of a young girl dealing with personal issues with the assistance of, or mostly just with the accompaniment of, traditional Japanese supernatural entities. And it's not a Studio Ghibli film--it's A Letter to Momo (ももへの手紙)
from Production I.G., written and directed by Hiroyuki Okiura. There's a self-consciousness about its emulation of Ghibli, and an insubstantiality to elements in the film that Okiura seems to have borrowed from Ghibli without really understanding. But there's something inevitably fascinating about good hand drawn animation, which creates a character of Momo almost in spite of the writing and direction, and the three supernatural entities she's forced to live with are very entertaining. There's a sweetness in the movie's main plot, but mostly what succeeds about this film are the things that seem to be second nature to the filmmakers, and are what make the movie worth watching.
Momo's an eleven year old girl recently moved with her mother to a small island community, where Momo's grandparents also live. Momo's father's recently died, and at the beginning of the film she listens to her grandfather's stories of him, from which her grandfather drifts into stories of his own father, telling Momo about some nineteenth century manga in the attic that his father collected.
Unbeknownst to Momo, three sentient water droplets have fallen from heaven, soon to take possession of characters in the book, shown to us in the first of several distinctly non-Ghibli digressively voyeuristic shots of Momo's body, in this case her feet.
There's nothing really gained by having a trio of supernatural beings pretending to be another trio of supernatural beings, it seems more like a disappointing lack of faith on Okiura's part that audiences would accept the reality of their more entertaining form.
Momo, essentially the only one who can see the three "guardians", finds herself put upon by them, having to cover for their penchant for stealing from nearby crop fields along with pinching various valuables from people's rooms.
They're all entertainingly animated and written, my favourite probably being the good natured and forgetful little Nosferatu looking guy, who offers to break one of heaven's rules for Momo, rationalising it'll be okay because he's forgotten the rules.
The title of the film concerns a letter Momo would like the guardians to deliver to her father in heaven, apologising for insulting him just before he died. It's a sentimental bit of plot business standing in for the grief and sense of loss in Momo and her mother the film can't effectively convey. It winds up not being half as effective as the scene where two of the guardians attempt to steal and eat a couple of boar piglets.