Kaori Sakuragi resided in the Strawberry Dorms while attending St. Miator's Girls' Academy on Astraea Hill. Frail with pale skin, she had neck-length black hair usually secured by a large pink hair bow and droopy ruby red eyes, a combination peers like Miyuki Rokujō and Shizuma Hanazono noted as beautiful. Her non-uniform clothing favored a feminine, simple, and elegant style.

Initially quiet and reserved, Kaori blossomed into a kind and lively person who cherished time with friends. She carried a background of chronic illness from childhood that progressively worsened. Upon her arrival at Miator, the student council assigned Miyuki and Shizuma to ensure her positive experience. Kaori and Shizuma formed a deep bond, evolving into an intimate romantic relationship. Learning she had only three months left to live, Kaori agreed to become Shizuma's partner in the Etoile election, seeking a meaningful final experience together despite Miyuki's concerns about the physical toll. They won, but Kaori passed away shortly after, leaving Shizuma heartbroken.

Her deepest connection was with Shizuma, whom she met through Miyuki. Their relationship shifted from initial caretaking to mutual emotional dependence; Shizuma later reflected they "needed each other." Kaori expressed gratitude for Shizuma's role in her happiness alongside remorse for the grief her death would cause. With Miyuki, Kaori shared a close friendship; Miyuki provided steady support and care, initially opposing the Etoile participation due to health risks but supporting it upon learning it was Kaori's dying wish.

Kaori never met the later transfer student Nagisa Aoi, though Nagisa was noted to vaguely resemble Kaori in age, height, and facial features, causing complications in Nagisa's relationship with Shizuma. Tamao Suzumi, Kaori's classmate, appeared troubled when Kaori's name was mentioned, suggesting possible friendship.

Anticipating Shizuma's grief, Kaori left a letter hidden under the Etoile necklaces. Discovered over a year later, it expressed no life regrets, cherished their memories—especially their first greenhouse visit—and conveyed happiness at being protected by Shizuma's love. It also encouraged Shizuma to embrace new experiences and relationships beyond Astraea Hill. Recalling a moment of physical intimacy shared with Shizuma under moonlight outside the academy gates, Kaori wondered if Shizuma would remain "beautiful, strong, and perfect."

Kaori's surname, Sakuragi, combines "cherry blossom" (桜) and "tree" (木), while her given name, Kaori, means "flower, blossom" (花) and "weaving" (織). Her specific illness remains unidentified.