Akuyaku Reijou no Kyouji ~Kon'yakusha wo Ubaitotte Gishi wo Oidashita Watashi wa, Douyara Ima kara Hametsu Suru You desu~

Born a commoner, Wellmy Ernest climbed the social ladder when her mother married an earl. Emboldened by her new status, she relentlessly bullied her meek, same-age half-sister both at home and at school. Wellmy ultimately seized her sister’s inheritance and fiancé, forcing the girl into a marriage with the notoriously cruel Lord of Magic—a union her timid sibling was too powerless to resist. With every desire fulfilled, Wellmy believed she had secured her perfect future. However, everything changes when Wellmy receives an invitation to a late-night soiree hosted by the Lord of Magic. Assuming he intends to announce her sister as his fiancée, Wellmy attends with her parents, expecting a glamorous celebration. Instead, they walk into a tribunal condemning them for their abuse of her half-sister. Far from a disaster, this outcome is exactly what Wellmy had planned all along.