B-sides are indeed hard to determine. As someone mentioned earlier, Ayu has very few
true b-sides because true b-sides are usually excluded from the album. However, in cases like the HEAVEN single, I consider a song like Will to be a b-side simply because it's not featured in the title of the single, which means it's
not a double a-side.
Then she's got the two odd balls that I don't know what to make of... fairyland was released as "fairyland c/w alterna" and INSPIRE was released as "INSPIRE c/w GAME." I'm pretty sure those are the only two instances she ever did that. "Coupled with--" What exactly does that mean? Double a-side or a-side and b-side that is for some reason featured in the title? XD I personally feel that they are double a-sides.
Anywayyy~ Here's my list:
ayumi Will > HEAVEN
utada Fly Me To The Moon (In Other Words) > Wait & See ~Risk~
utada Simple and Clean > COLORS
ayumi ever free > vogue
I'll try to think of more later.