Yukari sneaks up on Sanae then proceeds to tie up and rape her. It's somewhat heavy on the non-consensual stuff but not loaded with creepy extreme fetishism. Just ye olde doujinshi ritual of saying hello; should be a pleasant and enjoyable read for most. Both the forced sex and pain parts of it are fairly moderate; they're used strongly but not forced to be extreme for the sake of extreme.
Personally I would call this just perfect for people who are into NC/BDSM but don't like looking at things that are forced to be unpleasant and ugly by the authors. It is a bit heavy, but in an enjoyable way.
Things it includes: -Forced sex -Pain -Humiliation
Things it doesn't include: -Men -Dirty/ugly/scary stuff -Mood ruining psychological pain