concept (and the rival group to my Soundscape girls, I just haven't worked out the actual characters yet):

a school idol group produced by a big company, the only thing separating them from pro groups is that they all happen to be in the same school & work during club time. the company saw the opportunity in the fame of school idols and their concept is really going to town on the whole school girl thing, but it's all manufactured.

fans love them for their high-quality ... everything, but among other idol groups, they're frowned upon. people are afraid that this is the turn school idols will inevitably take, and that the idea of "girls making everything themselves in their club" that school idols are all about won't be able to stand up against it.

the four girls themselves have clear stage personas, some radically different than their actual personality, as guided by the company. they work really hard, but in a different way than the other groups, much more like pro idols ...