I quite enjoyed the drama and it is not clear why it is condemned and it receives such bad reviews, it is a bit like an American drama, it is true, after all, it is a Netflix production. I don't understand why the viewers should compare it to other dramas. I think that beyond the plot, (which is not bad at all) there are some difficult social criticisms in it, concerning the humiliating attitude of parents towards their children, the humiliating attitude of the rich towards the poor, the humiliating attitude of teachers towards students and the humiliating attitude of students towards students (and this is seen in many Korean dramas. They all bring everyone to the edge of their mental endurance.
Maybe because I am also a mother of twins, the story touched a sensitive chord with me. ..it's also not clear why Netflix doesn't mean that in episode 7 after the subtitles there is another and very significant section for the end of the series ..that many viewers don't notice and think that the drama ends with the leading woman arriving at her mother's house?? The series had a great soundtrack, the actors were great...all in all, not a bad drama at all and since Netflix defined it as a "limited series", I guess there is no second season and it's a shame, because it was left with another murder that you can hardly understand who was murdered (perhaps on purpose) and the end open, and has the good man become the bad man?