Saaya Yamabuki, a third-year student at Hanasakigawa Girls' High School, serves as Poppin'Party’s steady rhythmic backbone as their drummer. Her bond with Kasumi Toyama began at their entrance ceremony, evolving into daily lunch meetups and shared shifts at the live house RiNG alongside Kasumi and Taki. As the eldest sibling in a family-run bakery, she assists at Yamabuki Bakery during school terms, overseeing chores and responsibilities for her younger brother Jun and sister Sana.

During middle school, her brief tenure with the band CHiSPA ended abruptly when her father’s illness compelled her to prioritize family over music, a choice rooted in her reluctance to impose on others. Years later, Kasumi’s persistent encouragement and her mother’s reassurance reignited her musical spark, culminating in her joining Poppin'Party to reclaim her passion.

Known for her gentle maturity, Saaya often stabilizes her friends’ emotions, though her reluctance to refuse favors—such as tutoring Hagumi despite a hectic routine—reflects her selfless tendencies. Her hobbies span photography, amassing colorful hair scrunchies, and watching baseball games, paired with an affinity for romance films and Cinderella-themed stories. She avoids raw seafood but savors spaghetti infused with garlic and chili pepper.

Physically, her long, curly dusty brown hair is swept into a high ponytail secured by a ribbon, contrasting with vivid royal blue eyes. Her wardrobe leans toward casual frilled off-shoulder blouses and pale yellow trousers. A peculiar quirk is her strained rapport with animals, which inexplicably shun or bristle around her.

Her journey intertwines reconciling CHiSPA’s unresolved legacy with her Poppin'Party role, aided by drummer Tomoe’s camaraderie and Moca’s frequent bakery visits. Embracing photography, she chronicles band milestones and crafts promotional content, all while harmonizing bakery duties, part-time work, and performances—a testament to her resilient, understated perseverance.