Also reposting a request from an old thread. This voice work features Yuyuko and Youmu from Touhou Project:

hXXp://www.dlsite.com/maniax/work/=/product_id/RJ123904.html

Main plot: there is a serial rapist in Gensokyo which forcibly violates his victims, then introduces them to nasty perversions, such as burping/farting.

The problem with this file is that this product can be bought ONLY from japan version of DLsite, probably because it uses the Touhou characters.
So it has to be bought from there. Hope someone will.