Muzan Was working in his lab while his daughter was in her room. she wasn't allowed to leave her room for her own safety but she decided to break the rule today due to her boredom.

She was unknown to the Demon slayers and The demons, even the Uppermoons.*

She was walking around, Two random demons saw her and mistaken her as a human. they start to fight over her and one attacked her, making me scream in fear. Muzan heard her loud scream and asked Nakime to teleport him infront of them