Man, you might just get me into idol stuff in my old days... Until recently, "idol" was basically synonymous with highly polished, overproduced and a squeaky clean image in my mind. So "underground idol" was basically an oxymoron to me. But this performance is really raw, in the good sense, i.e. gives an authentic impression. I really liked it!
When you say you've been talking with them (also in the 100-YOKAI post), do you mean on Twitter? Or are you in Japan and could actually meet them at events?