If the mask girl was a guy, there wouldn't be any yuri pandering "fanservice" for readers to cloud their judgement and they would call the character what she actually is; a bitter incel (or femcel in this case).
I forgot about this subplot...God, I hate yuri. It's just shoehorned into everything and feels so unnaturally integrated into stories to cause unnecessary conflict.
Or she's bi and she doesn't know it yet. @Xxjuggernaut
Not denying she's not into her friend, (that part is obvious from not only their interactions, from the gallons of blood she's just lost) just stating its a possibility. Hell, she even says that she'd be more comfortable with him if he was a Macho-man so who knows, that might be her "other" type, but that's just speculative. @Xxjuggernaut