Do we care about Hard mode mentioned in the title? Of course we do, SMT is already hard on Normal, you are doing Hard on your first playthrough you mad man! Have you realized yet that picking up dialog and quest choices that please Yoko is shifting you towards Chaos alignment? Unless you are looking to be Chaos aligned, you should stop trying to please her, she won't leave because of you disagreeing with each other, she will leave and come back as the story demands it.