Miyuki Sakaki is a high school student who becomes trapped in an abandoned school building alongside several classmates and a teacher after receiving a threatening note filled with personal information. She is described as headstrong and notably resistant among the group, a trait symbolized by her refusal to remove her school uniform top even after capture, as the uniform represents her unwillingness to fully surrender. To humiliate her for this defiance, the antagonist singles her out and forces her to wear a BDSM dog collar. In appearance, Miyuki has medium-length black hair and brown eyes, and she typically wears a school uniform consisting of a white sailor-collared blouse with a red vest, a short red ribbon, and a brown pleated skirt, sometimes with her hair in a single braid. Her role in the story is that of one of the girls held against their will, and her stubbornness marks her as a particularly challenging target for her captor. No information is available about her specific background, personal motivations, key relationships, character development, or notable abilities beyond what is described.