Cash Cow Franchise: Many would argue that this is what Hamasaki's 15 year-long career has become. It's rather difficult to argue it too, seeing as this is the music industry we're talking about.
Executive Meddling: Avex, her record company, tried to force her to release a greatest hits album, which she felt was premature. They also played up the supposed rivalry between Ayu and Utada Hikaru, in the interest of sales, which Ayu denied vehemently. She was none too pleased with the entire situation, as evidenced by her iconic choice of album art for A BEST.
Hitless Hit Album: The five singles from A Song for XX were average/mediocre sellers... and then the album itself sold almost 1.5 million.