Reimu and Marisa in post #429698 are wearing it too.
In fact, looking at the tags in pixiv for it and post #736413 made me find out that it's tangentially related to Shichi-Go-San ( http://en.wikipedia.org/wiki/Shichi-Go-San ). Found out it's called "Hifu" (被布) and that it's usually worn by the 3 year old girls for Shichi-go-san (however, this particular picture is for the new year).