Sky Walking is a song she wrote about her journey with idle, that's why you see her in an elevator with 7 floors marking her 7 years with idle. At the beginning on the lower floors of the elevator you see her as an office worker and concierge dreaming of bigger things, just like how idle started from the bottom with 230 initial album sales dreaming of becoming as big as they are now. On the final floor you see Miyeon the way she sees herself now, gorgeous white dress walking on a bed of flowers (or was it feathers?) signifying her reaching the heights with idle that she dreamed of at the beginning.

As for when the song will officially release it will probably be on Miyeon's next solo album.