I dunno why, but I imagined Rin as Koishi. But I guess Satori makes more sense. Dem stubby arms. Also, Shizune should sooooo be Eiki. Misha could also be Iku. Lilly as Marisa is both hilarious and slightly unfitting. Lilly could be Yuyuko as well.
...Well, five out of six ain't bad. Really don't think Cirno was the right choice for Emi, though. Lessee, from a purely visual standpoint...I'd say Hatate would be the best fit. Fairly decent match on personality as well.