it looks like kiyoko was the only one that cut her pinkie even though they both agreed to do it which is interesting — most people are jumping at kiyoko for not going through with maintaining a relationship with mitsu, but the little hints and actions you can see is that kiyoko lost faith and felt that their promises were breaking and mitsu did nothing to stop it is a common theme in these chapters — kiyoko's depressive nature and mitsu's happy-go lucky attitude just covers up that.