Interesting enough that certain music genres these days seem to be more popular than the singers themselves
In my opinion it's hard to say Ayu is making J-Pop. I am OK with others puting her into that genre corner but for me she and her staff are simply producing high-end music.
New bands are aiming for a category that apparently stands for a successful range of possibilities to establish a musical product.
The small difference that puts Ayu above this confusing trend-genre story is the fact that she's a genre herself. During the past 15 years Ayu and her producers made it to a very own genre one could bravely call "Ayu pop"
if a label is needed for the direction of her musical art.
And... wow. That's more than any of the newest trendsetters will ever reach, no matter how cool and beloved they are today.