Apparently the Hirohashi Ryou joke is in reference to this thing, whatever it happens to be. Seems to be some kind of dog mascots/personifications for each of Japan's 47 prefectures.
Inami-chan is cosplaying Yuru Yuri's Ayano-chan you knowYayoi-san is Mado Magi's Sayaka-chan
Mado Magi = Mahou Shoujo Madoka MagicaWhat's going on Tanaeshima-san?That's unfair! Yamada also wants to wear a costume.By the way, I'm Hidamari's Yunnochi.Aoi-chan are you okay with that?