Musubu Torikiri is a character from the Climax Theater quest "School of the Heart" in the PSP release of Persona 2: Innocent Sin. She is a teacher at St. Hermelin High School during Persona 2: Innocent Sin. She appears to be shy, and acts skittish.
Musubu Torikiri was the older sister of Akari Torikiri, and after Akari was driven to suicide, Musubu grounded her spirit to the school unintentionally by continuing to mourn her over the years. She eventually grew up and became the homeroom teacher of Class 2-3, hoping to teach the students using a site called Ambrosia. The students proved too much for her to handle and she stepped down from the position, passing it on to Naozumi Kariyazaki. She recreated Ambrosia using the malevolent part of Akari's spirit and gave it to Kariyazaki, infecting him and the students with her Persona, a Parasite Persona that would brainwash them into abusing Akari's spirit to form into their "ideal" selves, in an attempt to provoke Akari's spirit into destroying the school.
Eventually Maya Amano came to the school to do an article on Kariyzaki's new found success using Ambrosia, and her party was thrown into the "Netherworld" by Kariyazaki. They defeated Kariyazaki and Persephone, the demon form of Akari's spirit, and went to confront Musubu, but decided not to after seeing Musubu scolded by her old teacher Minato, who convinced her to finally accept Akari's death and to confide in him about her problems.