I wonder if Transi's constitution causes people to give in to their worst impulses, because none of the deaths are like accidental.
You know, like teacher gets murdered because of the affair, girls commit suicide because of grief, other girl gets murdered out of jealousy, and so on.
This could also explain why Pieta is just going like murder crazy, with her being like hell yeah let's annihilate everyone. Transi's constitution is making her give in to her worst impulse that is "yeah fuck 'em who give a shit"