Hiroko Uchiyama attends Reverse Cross High School in a post-apocalyptic Tokyo. She possesses maroon hair cut to shoulder length and black eyes, typically seen in her school uniform, gloves, and star-motif earrings. She shares a romantic relationship with fellow student Kazu Shimada. This bond meets a tragic end when Hiroko is killed by the Tactical Fiend Hamuko. Kazu witnesses Hiroko's murder firsthand. Following her death, Hamuko removes Hiroko's face and cradles it over her breast as a trophy. Kazu Shimada becomes Hamuko's subsequent victim; she removes his face before consuming him. Later, during Kakugo Hagakure's battle with Hamuko, Kazu is regurgitated in a partially digested state. Hiroko Uchiyama's death and the desecration of her remains act as catalysts within the narrative, starkly illustrating the immediate threat of the Tactical Fiends and fueling the broader conflict confronting the protagonist.