Damn, I was not aware of this
There always leftover material (there must a bunch of it from the Party queen era, iirc she said it was almost made into a double disc album), and sometimes I get selfish and wish JPop was a bit more like Western Pop, with demos and photoshoots leaking as a whole, but then we also get so much material more frequently from Japan and I end up being okay with it... Still, self-composed songs from ayu being tossed aside sound so painful :/