If you loved Ein Brief an Momo, try Children Who Chase Lost Voices
Eine Brücke zwischen einem Film, den du schon gesehen hast, und einem, den kaum jemand kennt. Das teilen sie, und was der zweite macht, was der erste nicht macht.
Was sie teilen
Theyboth carry the bittersweet, foreign gem, tender mood tags, and they sit in Animation / Family / Fantasy territory. If that's the register that drew you to Ein Brief an Momo, the second film will land in a comparable space — through a different lens.
bittersweetforeign gemtender
What Children Who Chase Lost Voices is
Here's a film doing its level best to evoke Studio Ghibli. A lonely young girl, Asuna, follows a strange tune from her crystal radio into a hidden world. There, Asuna discovers not only the mythical land of Agartha but the pains of both love and loss. It's pretty and a decent homage, if nothing else.

