What is it?
The 2011 Japanese anime (animated) movie Children Who Chase Lost Voices (Journey To Agartha).
What is it about?
This is how MyAnimeList describes this anime (animated) movie:
If you could turn all your memories into a song, what would it resemble?
Between being an exceptional student and taking care of the house alone during her mother’s absence, Asuna Watase’s only distraction is listening to her old crystal radio in her secret mountain hideout.
One day, she accidentally tunes to a mysterious and melancholic melody, different from anything she has ever heard before.
Soon after, an enigmatic boy named Shun saves her from a dangerous creature, unknowingly dragging Asuna on a long journey to a long lost land bound to surpass her very imagination, turning her once melodic life into an intricate requiem.
[Written by MAL Rewrite]
This is how Crunchyroll describes this anime movie:
When she hears a strange song from a crystal radio, Asuna tunes into more than just a magical stream of music.
Soon, she is transported to a mysterious world where mythical beasts roam and brave warriors fight for their lives.
Agartha is a land of breathtaking beauty and unimaginable danger – a place where, it is believed, even the dead can be brought back to life.
But at what cost?