Subaru sensei hates incompetent people who has no willingness to spent bloody effort to meet her standard. Her rule is simple, follow my hellish road or go away like other normal person. Her two faced attitude is also the way she struggle to get general people recognition, because general people usually see the general attitude n general accomplishment.
She managed to get both accomplishment while masquerading a bright n caring attitude. No wonder she's the top star of the school.
ah, fuck, I got goosebumps, the mangaka is a fucking beast to make me hear things from images. Producing this into an anime would be so hard to make it justice.