Saaya Yamabuki is a third-year student at Hanasakigawa Girls' High School and the drummer for Poppin'Party. She formed a close friendship with her classmate Kasumi Toyama on the first day of high school, and the two have shared their daily lunches ever since. As the eldest of three siblings, she helps care for her younger brother Jun and younger sister Sana. Her family runs the Yamabuki Bakery, where she regularly assists, balancing this responsibility even during the school term. Before joining Poppin'Party, Saaya was the drummer for a middle school band named CHiSPA. She resigned from the band prior to a significant performance, not wishing to trouble her bandmates and family. In different accounts, this was due to either her father falling ill or pressing duties at the bakery. An original storyline also notes the passing of her mother. Kasumi’s encouragement and her mother’s past support rekindled Saaya’s enthusiasm for music, leading her to become the final member of Poppin'Party. She has royal blue eyes and long, curly dusty brown hair, which she usually fastens into a high ponytail with a ribbon. Her bangs are swept to the sides, complemented by curled, shoulder-length forelocks. She initially wore flowing pale yellow pants and a white, frilly off-the-shoulder top. Saaya is kind, empathetic, and diligent, often serving as the group's steady and mature presence. She readily assumes an "older sister" role, offering support during difficult moments and displaying a natural ease with children. Her agreeable nature sometimes makes it challenging for her to refuse requests from friends. Outside the band, she works part-time at the live house RiNG alongside Kasumi and Shirokane Taki. She maintains friendships with members of other bands, such as fellow drummer and older sister Tomoe Udagawa, and Moca Aoba, who enthusiastically supports the Yamabuki Bakery. Her hobbies include collecting hair scrunchies, karaoke, and watching baseball. She enjoys romance films and classic Cinderella tales. Her preferred foods are spaghetti aglio e olio and cheese, though she dislikes raw seafood. Following a particular event, she took up photography and often carries her camera. Animals typically react negatively to her, often biting, scratching, or fleeing when she approaches. She has also displayed the ability to play drums using three drumsticks, a skill referenced in both primary and alternate storylines. In an original storyline, she attended night classes and shared a desk with Kasumi, who attended during the day. They communicated by exchanging diaries left in the desk. In this version, she wrote her name in katakana as サアヤ. Her surname Yamabuki refers to the Kerria japonica flower and derives from "mountain" (yama) and "song" or "wind" (buki). Her given name Saaya means "sand" (sa) and "a thin type of silk fabric resembling satin" (aya).