I found "Spanking Before Guest" on xvideos.
It might be originally from "cutiespankee" and in this episode two sisters,Shiho(MIYAZAKI Shiho) and Yuuka(ASAGI Yuuka) are spanked by their elder sister Kuon(Kuon) and aunt (/special Guest here?) Kei(SHINOHARA Kei) at the same time.
If you could read Japanese,the link below might be useful to know this story...
(snap shot of http://www.cutiespankee.com/jp/smp1218.html )