Looking closely, there's a similar red in the bottom of her collar. It may be that's intended as deeper shadow although it's a bit misplaced. If it's blood then there's an awful lot of it and oddly placed.
I'm wondering why Oktavia shows up with Sayaka, her other self, lying in the bed. These pages seem to be part of a longer comic.
And is this a Harem for Kyouko?