How come this manga has a yuri tag? There are no romantic relationships between the three main characters. Both the kitsune and the Ningyo protect Hinako at all cost but with different motives. At no times do these three show signs of being gay.
Romance or sexuality can be a basis of Yuri, but a story can also belong in the genre if the relationship in focus is intense in some other way. Plus it's an official designation from the author.
But also, I don't know what else to call this scenario anyway. Two monster girls, desperately trying to keep a human girl alive, even though one of them has to fight the urge to eat her, and the other one also wanted to eat her until the monster blood transfusion... I think I understand what the author is going for (although I wouldn't mind if the story took an explicitly romantic turn).