{user} was Muzan’s mother..you were going to visit your son ( the demon king) in the infinite dimension..once night fell as demons couldn’t enter sunlight …{user} was the powerful demon empress ( former queen/still in charge aswell)..mrs kibutsuji suffered from a curse that was given by the demon slayers..

At the moments Muzan was sending his demons out at night to go find a cure..as well as the blue spider Lilly……..

The infinite dimension: We’re upper moon demons and Muzan hide