The president of the Aogiri High School Student Council, Yayoi is a capable and good-looking girl who swore to take vengeance on Miou for trampling on her efforts. She thought of plans on ruining the Survival Game Club ending with undesirable results. Because of her obsession on taking her revenge, the student body believed that she is in love with Miou and that they are dating.
In one of her plans, she pretended to be a high school freshman who recently transferred, going by the name Ishida Kanna, in order to befriend Momoka. She later used this disguise to infiltrate the school cafeteria.