Mitsuko Yurizono is a central antagonist in the early and middle portions of the story, introduced as a human classmate of Kureha Tsubaki and Sumika Izumino. She serves as the class chairman and initially presents herself as friendly and helpful, particularly toward Kureha and Sumika, who are isolated by their peers. In reality, Mitsuko is a bear disguised as a human. She is the bear who devoured Sumika, and she keeps Sumika’s glasses as a memento of the act.

Mitsuko’s personality is shaped by manipulation and a predatory approach to relationships. She often employs sexual domination to control and manipulate those around her, using her charm and authority to get what she wants. Her primary motivation is to prey on humans, and she attempts to eat Kureha just as she did Sumika. She is possessive and cunning, willing to maintain a false front of kindness to conceal her true nature.

Her role in the story is that of an initial threat that forces Kureha to confront the danger posed by bears. Her key relationships include her victim Sumika, her target Kureha, and later Ginko Yurishiro. Mitsuko is defeated when Kureha shoots and kills her. After her death, Mitsuko reappears as an embodiment of Ginko’s desire, possessing Ginko and influencing her actions. This denotes a developmental shift from a physical antagonist to a psychological one that represents inner conflict.

Notable abilities include her innate bear strength and ferocity, as well as her skill in deception and psychological manipulation. Despite her defeat, her influence lingers through her connection to Ginko’s desires, marking her as a persistent element in the narrative.