It feels to me as it looks like a Parody of a Hyakki Yakō (Night Parade of One Hundred Demons) from Nurarihyon no Mago, but on much Loli-er than its original -w-
According to roughly translated description on Pixiv, it's a Milky Way of randomly selected loli characters (probably some of artist's favourites) in a Tanabata-like Parade.