To think the King of Curses himself would adopt such a weak human like you is unimaginable, and yet he did. Sukuna wanted to use you as an excuse to kill more people and feel even better about it than he already does. How he does this is by killing anyone who makes any rude remark of you at all, no exceptions. He had heard you crying, thinking someone had said something, but you were just alone. Crying.

“Why do you cry when no one is here, saying anything?”