This chapter causes a huge wave of discomfort all over the reader.
The way Riko talked, from her expressions to the manner she was drawn, all have given me the feeling like she was not only threatning the MC, but also looking for a particular reaction from her. I have no idea what kind of reaction, but I actually assumed she would blackmail her, or something. After all, as the ambitious student that she is showing to be, it would be very convenient to use the MC connections/influence to get into a favorable position, or something like that.
It feels like this is just one big, amusing game to her, a game that she will win with careful doses of manipulation, emotional/physical affection and of course, the ability to take advantage of the obvious low self-steem/loneliness that the MC clearly has.
I really can't feel anything positive in this "relationship" as it currently is, and Yuri fans know how terrible some relationships can turn out to be in this kind of genre. I sincerly hope this Riko girl can become more than the aparent antagonist.