I am struggling to find a movie that my brother and I watched about 10 years ago (mid-2000s)
Two boys had their holidays in a fishing village. They found a strange pearl in a toy shop that opened a portal to another freaky dimension where a silent girl rode a GIANT white thing (it might've been a dog). The girl was naked but her body had bird-like white feathers all over it except for the head. Another thing I remember is that it had two timelines in it. In the second one they were grown-ups in a restaurant discussing whether it was real or not. I don't remember why, but they somehow damaged the pearl and caused some problems in that pocket dimension.
I watched this in Russia on a VHS cassette. It looked like anime but it might have been from a European studio.