The top is the standard kosode (small-sleeved kimono) used in Bleach, just cut to a short skirt and without the hakama. If you want a pattern, Simplicity and Butterick (I think) do fairly decent kimono patterns that you can modify. I don't think she has any back bow to her obi, so it's easily enough simulated by just using wide sashes and probably velcroing them in the back (or fastening them some other way) -- it looks more like a simplified formal obi than anything else, to me.
Hopefully that's something of a starting point. Feel free to PM me if you have other questions -- I tend to forget to check the boards. There's also the Bleach board on cosplay.com and the bleach_cosplay community on Livejournal, both of which are excellent resources.
Good luck to you!
