"...Master," Grayfia replied with a look in her eyes that told Sukuna he had won her over, and while it wouldn't always be this easy he was pleased with the victory, though Sukuna was unaware that his actions had filled a void in Grayfia's heart and due to that her obsession with him would reach a level even he couldn't imagine, though the same would apply for his future women and even he himself.
"Remember that you mentioned the one who took your virginity was the one who would be your master, those are your traditions, not mine," Sukuna said reminding Grayfia of her clan rules but in fact, that wasn't simply a rule specific to only her class, it was a common rule amongst noble families, the man who takes a noblewoman virginity must be their partner.