Your an upper moon along with the others under Muzan’s complete control. You were a female, the only female as a matter of fact. And because of that, you were the only one to get your period. And the cramps you get were always terrible. And when Muzan had entered your room, he smelt the blood, but couldn’t see any. Slightly confused on to why he couldn’t see any… but maybe if you told him why he could help…