Kyoko Kirigiri is one of the students trapped within Hope's Peak Academy. She is a young woman with a tall and slender build, long lavender hair worn in a single braid on the left side, and distinctive purple eyes. Her standard attire consists of a white button-up shirt, an orange tie, a dark purple jacket, a short skirt, and long black boots. She is never seen without her black gloves.

Upon introduction, Kirigiri is an enigmatic figure, as she is the only student whose ultimate talent is not disclosed, leading to her being referred to as the Super High School Level???. This air of mystery is central to her early demeanor; she is stoic, reserved, and extremely logical. She rarely displays emotion, preferring to observe situations with a calm and analytical mind. Her speech is direct and often limited to what she deems necessary, and she typically acts independently rather than as part of the group. This detachment is not born of cruelty but from a disciplined mindset instilled in her from a young age.

Kirigiri's background reveals that she comes from a renowned family of detectives. Her grandfather, Fuhito Kirigiri, a strict and traditional man, took over her training and upbringing after effectively disowning her father, Jin Kirigiri. Fuhito raised her to prioritize the pursuit of truth above all else, a philosophy that shaped her into a formidable investigator but also contributed to her emotional guardedness. A tragic event from her childhood, in which she was prevented from seeing her dying mother because her grandfather prioritized detective work, left a deep emotional scar and solidified her complex relationship with her own feelings and family ties.

Her primary motivation throughout the story is to uncover the truth behind the killing game and the mysteries of the school itself. This drive is stronger than her fear of death or her concern for the group's social dynamics. She pursues clues relentlessly, often putting herself in dangerous situations to gather information. Her role in the story is that of a guiding force for the protagonist, Makoto Naegi. While other students descend into panic or manipulation, Kirigiri remains focused, using her exceptional deductive skills to lead the investigations into each murder. In the class trials, she serves as a crucial ally, providing key insights and correcting flawed reasoning, though she rarely states the conclusion outright, instead guiding Naegi to discover the truth for himself.

Her relationship with Makoto Naegi is the most significant in the narrative. Initially, she is distant and even uses him as a tool for her investigations, at one point placing him in danger as bait to gather information on the mastermind. This leads to a temporary rift between them, highlighting her pragmatic and sometimes coldly calculating nature. However, as the story progresses, she begins to develop trust in him, recognizing his unwavering optimism and fundamental decency as strengths rather than weaknesses. Naegi's consistent hope contrasts with her cynical logic, and she comes to value his perspective, eventually risking her own life to save him. This relationship marks her key development: she starts as a solitary figure who trusts no one and ends as a cooperative ally who understands the power of relying on others.

Kyoko Kirigiri’s notable abilities are her peerless detective skills. She possesses a sharp eye for detail, a vast knowledge of forensic investigation, and a powerful capacity for logical reasoning and deduction. She can examine a crime scene and piece together the sequence of events with remarkable speed and accuracy, often reaching the correct conclusion long before anyone else. Her ability to remain completely objective allows her to see through lies and emotional pleas, making her an invaluable asset in determining the truth behind each murder.