(sorry for the picspam ><)
The photoshoot was exclusively Aoi and Uruha, so I'm sorry if this isn't the one you're looking for. I know ya' mentioned Reita, but I can't remember him in such an outfit o_o.
They're posing as oiran (花魁), or... um... well, let's just say they were a variation of geisha XD.
A much more promiscuous, higher-class, more expensive variation of the geisha, yeah...
As for the outfits, yeah, they're kimonos. Oiran wore some of the nicest kimonos known to the country at the time (they died out after the Edo period).
Here are the pics! Sorry about the page-stretching^^;.



