I think the last girl group/idol group Avex produced that I thought was good is SweetS.
Man I miss them...
They had a really interesting sound. Of course they had "idol" type songs, but they also had rather dark, mysterious, atmosphere-creating songs.
Love like candy floss is my absolute favorite. Considering their average age they were really cool.
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"Remember, don't let others dictate your music taste. If you like whatever you're listening to, keep listening to it."