^ Tsuzura Hanatemari, a character from the spin-off Kakegurui Twin. I know nothing about the series in general but looking at some of the official art, I can see why people would ship her with Mary.
^ She calls Mary her "prince" and they're the main two characters of the Kakegurui Twin spinoff. White-haired girl up on the top-left is also in the spin-off, as the antagonist who's intrigued by Mary.