Satō presents a human facade at Enoshima College, a setting plagued by mysterious attacks targeting female students. This human guise masks the character's true nature as a monstrous Replinoid. Originating from a future timeline dominated by such creatures, Replinoids are biologically engineered or evolved monsters that threaten humanity, specifically preying upon women to inflict violence and gruesome transformations. As the Replinoid responsible for the college attacks, Satō acts as the primary antagonist. These actions ignite the central conflict, directly prompting the intervention of the time-traveling protagonist, Megumi Iijima.