I know this is kinda vague, but the doujin I'm searching for features a multitude of girls and guys, who come together in the end for one of the girls to test her drugs.
The character I remember is a short black haired girl with a bowl cut that's usually displayed expressionless, she played another role in another doujin as the expressionless head of the photography club who fucked one of the members for a contest to avoid the disbanding of the club.
The art style often features shiny nude body parts.
I hope someone knows what I'm talking about :D
I think it's from the same author as Niku Jiru - Sakazaki Freddie, but I can't find it. He might only have done some art, but it's the same style