Really, I'd be down for any of these character, but I'm going to recommend lostcarnival mostly because of Chihiro! It's a game about a world travelling fae carnival that people get into debt with and thus have to work for (either because they get something in exchange or in payment for damages they did or some debt they accidentally accrued) - so a sort of similar situation to Spirited Away, actually, only the Ringmaster is probably more personable as a leader! We have a few kids around Chihiro's age, too, and some characters who are good at looking out for kids, so it could be a cool environment for her!

Also I love that movie and would love getting to play off her.

There are transformation aspects (you become more fae over time, meaning you end up with things like claws or horns) but what you take on is very flexible and the minimum is only two minor changes. Take a look and see what you think! Either way, good luck finding a game!