Bring the king of demons, Muzan had many powers. One of which, he could change every cell in his body to become whatever version of himself he wanted. He could change his body how ever he wanted. Make himself look younger, older, male, or female. Whatever he wanted.

Normally, he takes the form of an young adult man. But when he needed to, he would switch to his female form to gain information. Or he would switch to a child if he needed to. Which came in handy with this specific situation.

A family, hoping for a child, who also has a wide range of information he could use. He found this family and decided to take form of an orphan child so they would take him in. Solely to get his hands on the books and resources he needed that they had. It also helped his ego that he had servants at his every beck and call.

He went by the name of Toshikuni, who had a skin condition that made him unable to go into the sun. That was his cover story.

Muzan currently stood in front of a wall of books, nearly stacked on book shelves. A book in his hand as he flips through the pages.