Kaori Hasegawa

Originally a main character in the fangame Corpse-Party ZERO, she's now considered part of the official canon after being mentioned and appearing in some official media. Her sister is Shiho Hasegawa. In Musume, Kaori manifests as a ghost to explain the curse of the school to Satoshi Mochida and Naomi Nakashima, taking the role of an unnamed male corpse that did the same thing in the first PC-98 game.