I can already see the picture the author is drawing here, this is a set up for the female teacher to get away with her wrong doings as if she wasn't grooming the kid, by shoving into the story an even bigger scumbag in the form of a male teacher that pays one of his students for sex, while he schemes on the side for ways to get laid with the bad female teacher
That way once the scumbag teacher inevitably assaults the scumbag female teacher, and he is also caught fucking his students, the female teacher gets the perfect cover to distract everyone from her own bad behavior and slide away from trouble while the other guy sponges all the flack
And yes Maki is whoring herself, but it is still the adult that is at fault here, so i wont slut shame her, plus she is right, so far all the adults shown have been scumbags, even Kuroki who suspects that his coworkers are up to no good, up is not really doing anything about it, instead trying to pass it as if it were the student's responsibility to not fall astray