somethingsomething said: That thing down by Aya makes me think of Okuu, but they're just not similar enough for me to be certain about adding the tag.
The ribbon and the Yatagarasu Eye is a dead giveaway. It's just the triangular form is a crow character from Nichijou.
Youmu is DEFINITELY wearing Menma's dress from AnoHana. Kyouko is doing Ranka Lee from Macross Frontier. Rinnosuke looks like he's doing Moe Moe Kyun~<3. Maybe something to do with Idol Master, I don't watch it so I don't know. Well tagging what I know.
Suwako's rocking a frog version of the Penguindrum hat, I think.
Who's the Old Maid at the far right? It's Byakuren, Kanako, Yuyuko, Eirin, and ?. Process of elimination says Yukarin, but it could be Yuukarin. Also, shouldn't they be tagged?