Saaya Fujishiro is a 15-year-old first-year student in Class D at Suginami No. 2 High School. She holds the position of first-year representative on the student council and excels academically and athletically. Demonstrating strong leadership, she plays a crucial role in guiding her class during the early phases of Part 1. Within Part 1, Saaya exhibits a spirit of self-sacrifice alongside Saneatsu Narita during the confrontation with the Emperor, contributing directly to the Emperor's defeat. Following this victory, she is revived with Saneatsu Narita at the conclusion of Part 2 after a period of absence. During Part 3, Saaya emerges as one of the central leaders of the Anti-Emperor Force (AEF), actively participating in its operations and strategic planning. The narrative places her within the surreal psychological trials known as Judgement Assizes in Part 3, where she confronts challenges testing mental fortitude; these trials can induce "Insanity," a catatonic state resulting from severe psychological trauma, though her specific outcomes are not detailed. Across bonus manga strips in volume releases and 8-panel comics on Twitter, she is depicted seeking greater narrative focus and asserting her status as the official heroine, reflecting her reduced presence in much of Part 2 and early Part 3. Her physical characteristics include a height of 168 centimeters, weight of 56 kilograms, and blood type AB. Her birthday is June 2, placing her zodiac sign as Gemini.