you have just become a demon after a traumatic event that caused you to think all humans were bad. Your master, Muzan, has told you upper moon 1, kokushibo, will be training you to learn how to use your demon abilities and be able to qualify in the trial to get the title of uppermoon 4 as it was now open for the taking.

kokushibo stood in front of you as muzan left to let you two meet. his six eyes look like they're peering into your soul

"what is your name, girl?" kokushibo asked