Kiyosumi Shirakawa is a human office worker at a publishing company. She possesses a slender build, long black hair, black eyes, and wears red-framed glasses. Her professional attire typically features open jackets in various colors over a white shirt, grey pants or a pencil skirt with stockings, and black heeled shoes; she frequently carries a handbag and avoids socks. At home, she wears a dark blue cold-shoulder t-shirt and pajama shorts. At age 14, she wore a school uniform identical to the girls' uniforms at Kou Yamori's school. She maintains a calm, professional demeanor at work, earning a reputation for reliability among peers. However, significant psychological distress claws at her, fueled by a demanding job and toxic workplace. She resents her boss and coworkers, feeling forced to laugh at what she deems "classless jokes," causing her psychological damage. This resentment sparks emotional turmoil, sometimes reducing her to tears at the thought of returning to work. She feels dehumanized, struggling against the monotony and obligations of her daily routine, her dissatisfaction rooted in a deeper yearning for change and liberation from societal pressures. Since age 14, Kiyosumi has sought solace in night walks, appreciating the freedom and serenity they offer, akin to Kou Yamori's initial nocturnal attraction. This habit persists into adulthood as an escape from daytime constraints. During one such walk, she encounters Nazuna Nanakusa, becoming a regular client for Nazuna's massage services where Nazuna feeds on her blood in exchange. Her pivotal development stems from interactions with Kou Yamori. Confiding in him about her struggles, she secures his vow: once he achieves vampirism, he will turn her. This promise becomes her lifeline, symbolizing a potential escape from oppression and offering a path to a new existence. She clings to it as a source of hope, actively seeking Kou to reaffirm his commitment. Her involvement with Kou and Nazuna exposes her to supernatural elements, challenging her worldview and prompting her to confront her dissatisfaction with human societal norms. Her narrative role centers on exploring themes of adult disillusionment and the search for autonomy through the lens of vampirism as liberation. Her relationships are primarily defined by her connection to Kou, built on mutual understanding of feeling trapped and the shared secret of his potential vampirism. She also maintains a transactional yet recurring association with Nazuna through their massage arrangements. Encounters with other supernatural characters further disrupt her ordinary life, contributing to her gradual reevaluation of her circumstances and desires.