Shiori Sakurazaka stands as a central narrative figure with chest-length brown hair typically arranged in low braided pigtails, loose strands framing her face, and distinctive lime-green eyes. Her standard attire includes the school uniform: a light-blue collared shirt, dark-blue short skirt, medium blue bow, white knee-high socks, and brown shoes, occasionally layered with a beige sweater vest in adaptations. Sundresses serve as her preferred casual wear beyond academic settings.

Her background roots her as Jirō Yakuin's childhood friend since elementary school. During that period, classmates bullied her—particularly Ōmae—due to perceived clumsiness in relay race practices. This culminated in her feigning illness to avoid school, prompting Jirō to intervene with private baton-exchange training. His support resolved the crisis and cemented their enduring bond.

Personality-wise, she exhibits a gentle, kind, and reserved demeanor, often displaying shyness in social interactions. This reserve stems partly from middle school experiences involving male peers' inappropriate behavior, including non-consensual photography and overhearing lewd conversations about a teacher. These events fostered wariness toward boys, contributing to initial difficulties in her assigned couples training partnership with Minami Tenjin. Early evaluations suffered from her anxiety and discomfort, yielding low scores. Academically proficient, she achieves high marks and tutors peers like her best friend Mei Hamano. Conversely, she struggles with physical coordination, historically ranking poorly in relay races and displaying inflexibility during cheerleading. She also shows susceptibility to fear, reacting strongly to "Test of Courage" challenges or spiders.

Her relational dynamics form a core character arc. Feelings for Jirō Yakuin emerged in middle school, though she inadvertently friend-zoned him during their second year by expressing a wish to "remain friends forever." This unrequited affection persists alongside her awareness of Mei Hamano's undisclosed romantic feelings toward her, which she neither reciprocates nor consciously acknowledges. As Minami Tenjin's couples training partner, their relationship evolves from functional cooperation—equitably sharing duties like cooking—to gradual emotional openness. Encouraged by Jirō, she strives to improve their partnership despite initial setbacks, eventually confiding in Minami about personal matters, including unresolved feelings for Jirō. Her indirect connection to Akari Watanabe through mutual ties to Jirō positions her within a complex emotional triangle.

Key developments highlight incremental growth. Through couples training, she confronts apprehensions about male interactions, building confidence with Minami and achieving multiple A-Rank evaluations. The elementary school relay incident underscores early resilience and Jirō’s foundational support. While navigating romantic uncertainties, her journey emphasizes emotional maturation within interconnected relationships.

Her name carries symbolic weight: "Shiori" blends "poem" (詩) and "weave" (織), while "Sakurazaka" combines "cherry blossom" (桜) and "slope" (坂). Her surname references Sakurazaka Station, aligning with a naming convention for other characters.