You said "each of the 5" so you included Mai, but I still struggle to see her as anything but a "perfect idol". Would you or anyone else please explain what else do you see in her?
I can only directly go off the manga adaptation because I'm not personally reading the novels, so I have to go off what I've heard/seen reported from other readers who have gotten further (without giving spoilers) -
While she is literally an idol of sorts (or at least an internationally recognized model), she's also "sheltered" in the sense that she just assumes she's entitled to whatever catches her fancy in the moment - which lead to the trouble around her character SAing Renako fairly early on in the series.
But she grows from there and expands her worldview and her sense of humility and temperament, and becomes less "idol-like" in that regard and more down-to-earth toward the others.
That's a very broad summation that excludes a bit of nuance and context (both to not give spoilers and also because I don't want to write a novel's worth of comment at the moment) - but she does gain complexity to her character as the narrative goes on, at least relative to where she started.
