Sora Matsuzaki, whose name means "sky," is the younger sister of Umi and older sister of Riku. She lives with her siblings and grandmother, Hana Matsuzaki, at Coquelicot Manor, a boarding house overlooking Yokohama Port. Her mother, Ryoko Matsuzaki, works abroad as a medical professor, making Umi primarily responsible for the household. Sora attends Konan Academy alongside Umi.

Sora sports a bob haircut secured by a pink barrette on the right side and wears the Konan Academy sailor uniform with a green ribbon bow. Her traits often reflect those of a typical teenage girl, like prioritizing grooming her hair before breakfast. She develops a passing admiration for Shun Kazama after seeing his daredevil stunt at school, leading her to join his fan club. She asks Umi to accompany her to the Latin Quarter clubhouse to get Shun's autograph, inadvertently sparking Umi's relationship with Shun and involvement in saving the clubhouse from demolition.

Though less domestically involved than Umi, Sora assists during key moments, such as temporarily taking over cooking duties. She participates in the Latin Quarter renovation effort, burning discarded furniture alongside Shun. Her talkative nature provides exposition about school events and figures like student council president Shirō Mizunuma. Her initial superficial crush on Shun evolves into genuine affection for Shirō after he escorts her from the clubhouse.

Sora supports Umi through emotional struggles related to Shun, though her help with household chores remains inconsistent. During the climax, she joins the choir performance for chairman Tokumaru, contributing to his decision to spare the Latin Quarter. This journey shows her subtle maturation from a starstruck fan into someone capable of deeper attachments and situational responsibility.