MangaGamer has released a trial version (link NSFW) for Cartagra ~Affliction of the Soul~, a mystery/horror VN. Created by Innocent Grey of Kara no Shoujo fame, Cartagra was actually released three years prior to the release of KnS. The English Kara no Shoujo translation was released quite a ways before Cartagra’s, which may have to do with a fan translation project taking it on before MangaGamer’s official release.
Cartagra is set four years before the events of Kara no Shoujo, and from what I can tell, you should probably read Cartagra first before proceeding to KnS. Here’s a quick description, courtesy of TLWiki:
The hero of this story is Takashiro Shugo, An ex-police officer that is now unemployed and freeloading at a brothel. From time to time he takes on detective work from his former superior. As the story starts off, a missing persons case is dumped onto him.
The person he is supposed to find is Kohzuki Yura, a girl he had an intimate relationship with before being sent off to war. While all this is being played out, a series of brutal killings occur in the background. As they strike closer to home, Shugo is no longer able to turn a blind eye and is dragged into the spiraling web of events.
I heard a vague teaser about there being some nice extra at the end of the demo from an MG beta tester, though I have no idea what it could be exactly.
Presumably it’s loli-buruma. If you don’t have a MangaGamer account (or you’re just too lazy to log in), you can download the trial here instead.