Wolfpedia 

The Mystic Cave is an area from Balto 2. The cave is found when Aleu hears music and follows it to the place. Standing there is Muru (Field Mice). He twists around some of the crystals to show Aleu who she really is (and then a song comes on). after the song, Aleu looks around for Muru, but he is now inprinted on the wall (which somehow shows that he's a spirit). the name of this place is still unofficial.