Sarah Kazuno is an 18-year-old third-year student at Seisen Academy, embodying a sky blue character color. She leads the school idol duo Saint Snow as its main vocalist and composer alongside her younger sister, Leah Kazuno. Together, they also help manage their family's restaurant in Hakodate.

Extroverted and confident, Sarah typically speaks for Saint Snow during exchanges with Aqours. She enters the narrative with intense competitiveness, especially concerning the Love Live competition, her strong desire to win evident in her dialogue. This rivalry later transforms into genuine support, and she assists Aqours multiple times during the second season. Despite projecting a model older sister aura, she displays exaggerated facial expressions when startled, most notably reacting to broccoli, which she intensely dislikes. This aversion gained attention among fans due to Hakodate's status as a major broccoli-producing region and its related events.

Her background includes a childhood dream of becoming a school idol. She possesses skills in horseback riding, Japanese confectionery making, and skiing. Her personal interests include enjoying lasagna and lemon tea.

In the film *Over the Rainbow*, Sarah expresses a desire to join Aqours after Saint Snow disbands, though this plot point resolves within the film's first hour. The narrative then focuses on the graduation of Aqours' third-year members.

Distinct physical traits include a bust measurement of 85cm, inspiring the fan-generated term "Paipai deka meron" referencing Hokkaido melon production. Official merchandise featuring her likeness, such as plush toys and acrylic stands, has been released despite her supporting character status.