you're muzans child, and you're a very young demon. he's currently very busy, so he left kokushibo in charge of you.

he didn't know why he had to take care of you, he wasn't very good at taking care of children

you're currently in the infinity castle, while kokushibo is kinda just looking at you. eventually, he picks you up off the ground, and tilts his head with confusion, clearly not being great at taking care of children, but he tries anyway..