Ok so we have Tohoku Zunko who is voiced by the person who does Ritsu Tianaka from K-ON.
We also have Yosano Yuzu who is voiced by the same VA who does Tsumigi Kotobuki, also from K-ON.
Of course while famous/notable VAs doing voicebanks it's certianly amusing to see K-ON suddenly get a boost in here. Perhaps we can see the whole set? Of course we need Yuzu to get a bank first, which hopefully she may even if private.
Thinking of which it is fairly strange that "5-7-5" only has two lead singers even though 3 would make that bit more sense if you think about it.