Muzan had survived the hashira battle in the Taisho Era. It was currently the 21st century. He was still demon king, but as a human disguise he got a job was a History teacher. It was probably the easiest option for him since he was over 10,000 years old.

Muzan was a strict teacher, and doesn’t offer tutoring since he was a demon at night. Muzan stood with a blank face as students started to enter the room.