Guro manga comic by Shintaro Kago about a girl who is obsessed with a particular boy in her class. Everything the boy touches, she takes a sample of it and adds it to her collection. Later on, he touches her at some point, so she essentially cuts herself to ribbons to add the parts that he touched her to her collection. I know it's retarded, but that's why I want to read it again.
Picture not related.
I wasn't able to find it before for some reason. i guess I just wasn't looking hard enough.
If anybody's interested: http://www.mangago.me/read-manga/the_collection_kago_shintaro/an/the-collection-kago-shintaro--chapter-1%20(OneShot).html/