You have a good instrumental going on here, one that creates some good ambiance. Your lyrics play into it as well--they give the whole thing sort of an otherworldly, mysterious vibe. If you're looking for anything constructive, I noticed Miku wound up sounding a little metallic on some of her lower notes--maybe caused by an effect you were using or something. Assuming that's right, if you wanted, you could probably avoid that with some automation--turn the effect down or whatever during the lower notes. But maybe that's what you were going for--I'm not sure. It just seemed a little out of place, given what I thought was the more mystical character of the rest of the song. Either way, your song was enjoyable to listen to!