(Very mild spoilers ahead.)
It's necessary to point out immediately that the plot of Letter to Momo (ももへの手紙 – Momo e no Tegami) will sound more than a little familiar: a child, whose parent is suddenly absent, moves to the countryside with the other parent. While they are absent, working, she meets a mystical creature who, when a terrible event befalls her, saves the day by calling in a kind of spirit-vehicle. Yes, you've seen this before.
But there's more to this film than a mere Me-Too-Totoro. It's a darker story, aimed at a slightly older audience: Momo's father is not merely absent, but dead, and she's wracked with guilt over their last conversation, which was an argument. The letter of the title was found after his death – it begins 'ももへ' (Dear Momo), but ends immediately, and she carries this with her. She's left trying to navigate the difficulties of moving to a new town, full of teenage awkwardness, burdened with guilt and loneliness.
In fact, everything in the film is a touch harsher: the sad scenes are sob-inducing, and there's real peril in the dramatic moments. Meanwhile, the spirits Momo encounters along the way aren't as soft and cuddly as Totoro and the soots – instead they turn out to be goblin-like creatures with fierce visages and a troublesome case of kleptomania.
But all that said, this is a kids' film, and it all plays out beautifully. The animation is clean and crisp, and the whole thing reminded me of Mamoru Hosoda's lovely Girl who Leapt Through Time adaptation (buy it on DVD!). It's another example of how Japan's animated films can, on a good day, stand a mile above the drek that passes for most TV anime these days – if it ever makes it across to a UK DVD, then snap it up.
Note for Japanese learners: most of the language isn't tricky, with the exception of the goblins, who I often struggled and failed to understand.