Is it a sin to kill the person who took my daughter's life?

A mother in her late forties avenges the "murder" of her daughter due to malicious bullying by other mothers! What is the shocking revenge method taken by the mother in her anger and despair? Among many mothers in their thirties, Yuna Kawai was looked down upon by those around her as "unreliable" and "ignorant" due to her youth at 23 years old. Among them, Saori, whose husband is a prefectural assembly member, was part of the mother's group...